# TIP 444: Add "weekdays" unit in clock add
	Author:         Pietro Cerutti <gahr@gahr.ch>
	State:          Final
	Type:           Project
	Vote:           Done
	Created:        23-Feb-2016
	Post-History:   
	Tcl-Version:    8.7
	Tcl-Branch:     tip-444
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# Abstract

This TIP proposes an enhancement to the **clock add** command to support
performing days arithmetic using weekdays only.

# Rationale

The **clock add** command allows to perform time arithmetic using a variety
of time units, including days. However, it offers no easy way to skip
weekends. It is often desired to perform weekdays arithmetic that involves
adding or subtracting a number of non-weekend days to a certain date. This is
useful in example when computing delivery dates.

# Proposal

The **weekdays** time-unit is added to the list accepted by the **clock
add** command. The **count** argument represents weekdays \(Mon-Fri\) to be
added \(or subtracted in case of a negative value\) to the date. The result of
adding weekdays to a date is never a weekend day, unless the starting day is
itself a weekend day and **count** is 0.

# Reference Implementation

Available at <https://core.tcl-lang.org/tcl/timeline?t=tip-444>

# Discussion

A point has been raised as to whether _weekday_ is unambiguous enough. For instance, in Sweden there seems to be some disagreement on whether the translation _vardag_ includes Saturdays. As an alternative, the term _workday_ has been mentioned. This, however, has the downside of introducing the concept of working days vs. public holiday. Also, the working week is not Mon-Fri in all countries, see <https://en.wikipedia.org/wiki/Workweek_and_weekend#Around_the_world> .

TIP does not try to accomodate locale-specific features and characteristics. For this reason, it seems best to stick to _weekday_ as the name of the unit and specifically mention that \(Mon-Fri\) is intended in the documentation.

# Copyright

This document has been placed in the public domain.

