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Date::Manip::Delta(3) |
User Contributed Perl Documentation |
Date::Manip::Delta(3) |
Date::Manip::Delta - Methods for working with deltas
use Date::Manip::Delta;
$date = new Date::Manip::Delta;
This module contains functions useful in parsing and manipulating deltas. As
used in this module, the term delta refers to an amount of time elapsed. It
includes no information about a starting or ending time.
There are several concepts involved in understanding the
properties of a delta.
- standard and business delta
- There are two different modes for working with deltas: standard and
business. The mode used depends on how you treat the calendar.
Standard deltas use the full calendar without any
modifications.
A business delta uses a calendar in the way a business might.
In a business calendar, anything outside of a business day is ignored.
Typically, this includes holidays and weekends. In addition, the part of
the day outside of business hours is also ignored, so a day may only run
from 08:00 to 17:00 and everything outside of this is ignored.
The length of a work day is usually not 24 hours. It is
defined by the start and end of the work day and is set using the config
variables: WorkDayBeg and WorkDayEnd (WorkDay24Hr
may be used to specify a 24-hour work day). The work week is defined
using the config variables: WorkWeekBeg and
WorkWeekEnd.
Daylight saving time are ignored with business calculations
because time changes occur at night (usually on the weekends) outside of
business hours. This may yield unexpected results if the work day is
defined to be 24-hours and the work week includes a day when a time
change occurs.
- fields
- A delta consists of 7 fields: years, months, weeks, days, hours, minutes,
and seconds, usually expressed as a colon-separated string. For example:
1:2:3:4:5:6:7
refers to an elapsed amount of time 1 year, 2 months, 3 weeks,
4 days, 5 hours, 6 minutes, and 7 seconds long.
- normalized
- A delta can be normalized or not. A normalized delta has values which have
been simplified based on how a human would think of them. As an example,
the delta:
0:0:0:0:0:10:70
is not normalized since 70 seconds is typically thought of as
1 minute 10 seconds. The normalized form of this delta would be:
0:0:0:0:0:11:10
By default, deltas are converted to a normalized form in most
functions that create/modify a delta, but this can be overridden.
- Types of deltas
- There are 4 type of deltas that are available.
- Exact deltas
- The most common type (and the default in most situations) is an exact
delta. An exact delta is one where only fields which have exactly known
lengths are allowed to be non-zero.
For standard calculations, there are only three exactly known
fields (hours, minutes, and seconds). The lengths are defined as:
1 hour = 3600 seconds
1 minute = 60 seconds
Note that since a day is NOT always 24 hours (due to daylight
saving time changes), a day is not an exactly known field.
For business calculations, a day IS an exactly known field.
Since business mode ignores daylight saving time, the length of the day
can be calculated based on the config variables listed above. So, for
example, if the work day is 08:00-17:00, the length of the day is 9
hours. The length of the week is still unknown since some work weeks may
have fewer days than others due to holidays.
All fields which are not exactly known will always have zero
value.
- Semi-exact deltas
- A semi-exact delta treats the day/week fields as if they were exactly
known.
For standard calculations, this is done by using the
relationships:
1 day = 24 hours
1 week = 7 days
For business calculations, it is done by treating a week as a
constant length (determined by the config variables listed above)
ignoring holidays. So if a typical work week is Mon-Fri, the length of
the week is 5 days.
For semi-exact deltas, the value of the year/month must be
zero.
Although this may yield some values that are not exactly
accurate around daylight saving time transitions, strictly speaking,
they yield results that are useful in terms of how humans think of
deltas.
- Approximate deltas
- An approximate delta can have non-zero values for all fields. When
normalizing the fields, the year/month fields are treated as one set using
the relationship
1 year = 12 months
The remaining fields are normalized using the semi-exact
relationships.
- Estimated deltas
- The final type of delta are estimated deltas. These are deltas where an
estimated length is applied to all the approximate fields.
For standard deltas, the additional relationship:
1 year = 365.2425 days
is used. For business deltas, the additional relationship:
1 year = X/7 * 365.2425 days
(where X is the number of work days in a week) is used.
Fractional seconds will be discarded (not rounded).
NOTE: it is not possible to look at a delta and determine what
type it is. For example, a standard delta with a non-zero day value might be
approximate or semi-exact. The type will need to be explicitly selected, or
determined by the context of the operation.
- signs
- Each field has a sign associated with it. For example, the delta "1
year ago" is written as:
-1:0:0:0:0:0:0
The sign of any field is optional, and if omitted, it is the
same as the next higher field. So, the following are identical:
+1:2:3:4:5:6:7
+1:+2:+3:+4:+5:+6:+7
In a normalized delta, all fields in a set will have the same
sign. So the standard delta:
0:0:+3:-2:0:0:0:0 (3 weeks -2 days)
is not normalized. The normalized version would be:
0:0:+2:5:0:0:0:0 (2 weeks, 5 days)
Since an approximate delta has two sets (the y/m set and the
w/d/h/mn/s set), these deltas may have two signs. So, the following is a
fully normalized approximate delta:
+1:0:-3:3:1:0:0
- fractional values
- Fractional fields are allowed such as:
1.25 days
1.1 years
but whenever parsing a delta with fractional fields, the delta
will be normalized using the estimated relationships described above.
Fractional seconds will be discarded.
- new
- new_config
- new_date
- new_delta
- new_recur
- base
- tz
- is_date
- is_delta
- is_recur
- config
- err
- Please refer to the Date::Manip::Obj documentation for these methods.
- parse
-
$err = $delta->parse($string, \%opts);
$err = $delta->parse($string [,$business] [,$no_normalize]);
The second format is supported for backward compatibility, but
is deprecated and will be removed in Date::Manip 7.00. The second form
is equivalent to:
$err = $delta->parse($string, { business => $business,
nonorm => $no_normalize });
This takes a string and parses it to see if it is a valid
delta. If it is, an error code of 0 is returned and
$delta now contains the value of the delta.
Otherwise, an error code of 1 is returned and an error condition is set
in the delta.
Recognized options are:
mode : standard/business
to specify if it is a business delta or a standard delta
nonorm : 0/1
1 if the delta should not be normalized
type : exact, semi, approx, estimated
When specifying the type, the delta given must satisfy the
requirements of the type (i.e. no year field for an exact delta).
A delta string is usually specified in compact notation which
consists of a colon separated list of numbers (with optional signs):
Examples:
0:0:0:0:4:3:-2
+4:3:-2
+4::3
In compact notation, from 1 to 7 of the fields may be given.
For example D:H:MN:S may be given to specify only four of the fields. No
spaces may be present in the string, but it is allowed to omit some of
the fields. For example 5::3:30 is valid. In this case, missing fields
default to the value 0.
The delta string may also be specified using common field
abbreviations. This is described below in the "ADDITIONAL DELTA
NOTATIONS" section.
- input
-
$str = $delta->input();
This returns the string that was parsed to form the delta.
- set
-
$err = $delta->set(\%opts);
$err = $delta->set($field,$val [,$no_normalize]);
The second format is supported for backward compatibility, but
is deprecated and will be removed in Date::Manip 7.00. The second form
is equivalent to:
$err = $delta->set( $field => $val, 'nonorm' => $no_normalize );
This explicitly sets one or more parts of a delta.
%opts is a set of key/value pairs:
$key $val
delta [Y,M,W,D,H,MN,S] sets the entire delta
business [Y,M,W,D,H,MN,S] sets the entire delta
standard [Y,M,W,D,H,MN,S] sets the entire delta
y YEAR sets one field
M MONTH
w WEEK
d DAY
h HOUR
m MINUTE
s SECOND
nonorm 0/1
mode business, standard
type exact, semi, estimated, approx
An error is returned if an invalid data is passed in.
%opts can only include a single key
that affects each field (i.e. you can set delta or
business but not both, and you cannot set both delta and
y, but you CAN set both y and w).
When setting the entire delta with business or
standard, it flags the delta as a business or standard mode delta
respectively. In those cases, you are not allowed to set the mode
option. Partial deltas are allowed (i.e. [H,MN,S]) in which case zeros
are added for all fields not specified.
When setting the entire delta with delta, the flag is
left unchanged (unless the mode option is also passed in).
Also, when setting the entire delta, signs are not carried
from one field to another, so [-1,2,...] is equivalent to
[-1,+2,...].
By default, a delta is normalized, but setting the
nonorm key to a true value will not do that.
For backwards compatibility, normal can be used in
place of standard, both as $field or as
$val. This is deprecated and will be removed in
Date::Manip 7.00.
When setting any field in the delta, the type of delta will be
determined automatically as either exact (if only fields that are
exactly known are have non-zero fields), semi (if only fields
that are semi-exact or exact are included), or approx otherwise.
If the type option is set, it will be used provided it is valid
(i.e. you cannot set it to exact if fields that are not exactly
known are set).
- printf
-
$out = $delta->printf($in);
@out = $delta->printf(@in);
This takes a string or list of strings which may contain any
number of special formatting directives. These directives are replaced
with information contained in the delta. Everything else in the string
is returned unmodified.
A directive always begins with '%'. They are described in the
section below in the section "PRINTF DIRECTIVES".
- calc
- Please refer to the Date::Manip::Calc documentation for details.
- type
-
$flag = $delta->type($op);
This tests to see if a delta is of a certain type.
$op can be;
business : returns 1 if it is a business delta
standard : returns 1 if it is a standard (non-business delta)
exact : returns 1 if it is exact
semi : returns 1 if it is semi-exact
approx : returns 1 if it is approximate
estimated : returns 1 if it is estimated
- value
-
$val = $delta->value();
@val = $delta->value();
This returns the value of the delta. In scalar context, it
returns the printable string (equivalent to the printf directive '%Dt').
In list context, it returns a list of fields.
An empty string/list is returned if there is no valid delta
stored in $delta.
- convert
-
$delta->convert($to);
This converts a delta from one type to another.
$to can be 'exact', 'semi', or 'approx'. The
conversion uses the approximate and estimated relationships listed above
to convert the delta.
For example, if the exact non-business delta
$delta contains:
0:0:0:0:44:0:0
then the following call:
$delta->convert('semi')
would produce the semi-exact delta:
0:0:0:1:20:0:0
The result will always be normalized.
Converting from one type to another that is less exact (i.e.
exact to semi-exact or semi-exact to approx) is supported. Converting
the other direction is supported for backward compatibility, but will be
removed in 7.00 because that operation is not one that is well
defined.
There is currently no support for converting business to
non-business (or vice-versa).
- cmp
-
$flag = $delta1->cmp($delta2);
This compares two deltas (using the approximate relationships
listed above) and returns -1, 0, or 1 which could be used to sort them
by length of time.
Both deltas must be valid, and both must be either business or
non-business deltas. They do not need to be the same out of exact,
semi-exact, and approximate.
undef will be returned if either delta is invalid, or you try
to compare a business and non-business delta.
When parsing a delta, the string may be specified with the field spelled out,
rather than using the colon separated fields.
This expanded notation has the fields spelled out in some language
specific form:
Examples:
+4 hours +3mn -2second
+ 4 hr 3 minutes -2
4 hour + 3 min -2 s
4 hr 2 s
A field in the expanded notation has an optional sign, a number,
and a string specifying the type of field. If the sign is absent, it
defaults to the sign of the next larger element. So the following are
equivalent:
-4 hr 3 min 2 sec
-4 hr -3 min -2 sec
The valid strings describing each of the fields is contained in
"Delta field names" section of the appropriate
Date::Manip::Lang::<LANGUAGE> document. Refer to the Date::Manip::Lang
document for a list of languages.
For example, for English, the document is
Date::Manip::Lang::English and the field names include strings like:
y: y, yr, year, years
m: m, mon, mons, month, months
w: w, wk, ws, wks, week, weeks
d: d, day, days
h: h, hr, hrs, hour, hours
mn: mn, min, mins, minute, minutes
s: s, sec, secs, second, seconds
This list may not be complete. You should refer to the language
document for the full list.
The "seconds" string may be omitted. The sign, number,
and string may all be separated from each other by any amount of whitespace.
The string specifying the unit must be separated from a following number by
whitespace or a comma, so the following example will NOT work:
4hours3minutes
At minimum, it must be expressed as:
4hours 3minutes
4 hours, 3 minutes
In the the expanded format, all fields must be given in the order:
Y M W D H MN S. Any number of them may be omitted provided the rest remain
in the correct order. Small numbers may be spelled out, so
in two weeks
in 2 weeks
both work (but do not rely on this to work for large numbers).
Most languages also allow a word to specify whether the delta is
an amount of time after or before a fixed point. In English, the word
"in" refers to a time after a fixed point, and "ago"
refers to a point before a fixed point. So, the following deltas are
equivalent:
1:0:0:0:0:0:0
in 1 year
and the following are equivalent
-1:0:0:0:0:0:0
1 year ago
The word "in" is completely ignored. The word
"ago" has the affect of reversing all signs that appear in front
of the components of the delta. In other words, the following two strings
are identical:
-12 yr 6 mon ago
+12 yr +6 mon
(don't forget that there is an implied minus sign in front of the
6 in the first string because when no sign is explicitly given, it carries
the previously entered sign).
The in/ago words only apply to the expanded format, so the
following is invalid:
1:0:0 ago
A delta may be standard (non-business) or business. By default, a
delta is treated as a non-business delta, but this can be changed in two
different ways.
The first way to make a delta be business is to pass in the
appropriate option. For example:
$delta->parse($string, { 'mode' => 'business' });
$delta->parse($string, { 'mode' => 'standard' });
The second way to specify whether a delta is business or
non-business is to include a key word in the string that is parsed. If this
string is included, it should not conflict with the value of a 'mode'
option.
Most languages include a word like "business" which can
be used to specify that the resulting delta is a business delta or a
non-business delta. Other languages have equivalent words. The placement of
the word is not important. Also, the "business" word can be
included with all types of deltas, and in both compact and expanded
notation, so the following are valid and equivalent:
in 4 hours business
4:0:0 business
business 0:0:0:0:4:0:0
There are also words "exact" or "approximate"
which may be included in the delta for backward compatibility. However, they
will be ignored. They will be removed in Date::Manip 7.00. The accuracy of
delta (exact, semi-exact, approximate) will be determined only by what
fields are present in the delta and the options passed in. When a delta is
parsed, it is automatically normalized, unless the 'nonorm' option is passed
in.
The following printf directives are replaced with information from the delta.
Directives may be replaced by the values of a single field in the delta (i.e.
the hours or weeks field), the value of several fields expressed in terms of
one of them (i.e. the number of years and months expressed in terms of
months), or the directive may format either the entire delta, or portions of
it.
- Simple directives
- These are directives which print simple characters. Currently, the only
one is:
%% Replaced by a single '%'
As an example:
$delta->printf('|%%|');
=> |%|
- Directives to print out a single field
- The following directive is used to print out the value of a single field.
Spaces are included here for clarity, but are not in the actual directive.
% [+] [pad] [width] Xv
Here, X is one of (y,M,w,d,h,m,s). The directive will print
out the value for that field.
If a '+' is included immediately after the '%', a sign will
always be included. By default, only negative values will include a
sign.
'width' and 'pad' are used to set the width of the string
containing the field as well as how it is padded.
'width' is any positive integer (without a sign). If 'width'
is included, it sets the length of the output string (unless the string
is already longer than that, in which case the 'width' is ignored).
If 'pad' is included, it may be the character '<', '>',
or '0'. It will be ignored if 'width' is not included, or the string is
already longer than 'width'. If the formatted delta field is shorter
than 'width', it will be padded with spaces on the left (if 'pad' is
'<'), or right (if 'pad' is '>'), or it will be padded on the left
(after any sign) with zeroes (if 'pad' is '0').
In the following examples, $delta
contains the delta: 1:2:3:4:5:6:7
$delta->printf('|Month: %Mv|');
=> |Month: 2|
$delta->printf('|Day: %+05dv|');
=> |Day: +0004|
$delta->printf('|Day: %+<5dv|');
=> |Day: +4|
$delta->printf('|Day: %>5sv|');
=> |Day: 7 |
- Directives to print out several fields in terms of one of them
- The following directive is used to print out the value of several
different fields, expressed in terms of a single field.
% [+] [pad] [width] [.precision] XYZ
Here, X, Y, and Z are each one of (y,M,w,d,h,m,s). The
directive will print out the value for fields Y through Z expressed in
terms of field X.
Y must come before Z in the sequence (y,M,w,d,h,m,s) or it can
be the same as Z.
So, to print the day and hour fields in terms of seconds, use
the directive:
%sdh
Any time all of X, Y, and Z are from a single set of fields,
exact relationships are used.
If the X, Y, and Z fields do not all belong to the same set of
fields, approximate relationships are used.
For non-business deltas, an approximate relationship is needed
to link the Y/M part of the delta to the W/D part and a semi-approximate
relationship is needed to link the W/D part with the H/MN/S part. These
relationships are:
1 day = 24 hours
1 year = 365.2425
For business deltas, the approximate and semi-approximate
relationships used to link the fields together are:
1 week = X (length of business week in days)
1 year = X/7 * 365.2425
For business deltas, the length of the day is defined using
WorkDayStart and WorkDayEnd. For non-business deltas, a day is 24 hours
long (i.e. daylight saving time is ignored).
If 'precision' is included, it is the number of decimal places
to print. If it is not included, but 'width' is included, precision will
be set automatically to display the maximum number of decimal places
given 'width'.
If 'pad' is included, it may be the character '<', '>',
or '0', and is used in the same way as printing out a single field.
In the following examples, $delta
contains the delta: 1:2:3:4:5:6:7
$delta->printf('|%.4Myw|');
=> |14.6900|
1 year, 2 months, 3 weeks is approximately
14.6900 months
- Directives to print out portions of the delta
- The following directives may be used to print out some or all of a delta.
% [+] [pad] [width] Dt
% [+] [pad] [width] DXY
The first directive will print out the entire delta.
The second will print out the delta from the X to Y fields
inclusive (where X and Y are each one of (y,M,w,d,h,m,s) and X must come
before Y in the sequence).
'pad' is optional and can be either '<' or '>' meaning
to pad on the left or right with spaces. It defaults to '<'.
If a '+' is included immediately following the '%', every
field will have a sign attached. Otherwise, only the leftmost field in
each set of fields will include a sign.
$delta->printf('|%Dt|');
=> |+1:2:+3:+4:5:6:7|
$delta->printf('|%+Dyd|');
=> |+1:+2:+3:+4|
Please refer to the Date::Manip::Problems documentation for information on
submitting bug reports or questions to the author.
Date::Manip - main module documentation
This script is free software; you can redistribute it and/or modify it under the
same terms as Perl itself.
Sullivan Beck (sbeck@cpan.org)
Visit the GSP FreeBSD Man Page Interface. Output converted with ManDoc.
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