'\"
'\" Generated from file 'defer\&.man' by tcllib/doctools with format 'nroff'
'\" Copyright (c) 2017, Roy Keene
'\"
.TH "defer" 3tcl 1 tcllib "Defered execution ala Go"
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.SH NAME
defer \- Defered execution
.SH SYNOPSIS
package require \fBTcl  8\&.6\fR
.sp
package require \fBdefer  ?1?\fR
.sp
\fB::defer::defer\fR ?\fIcommand\fR? ?\fIarg1\fR? ?\fIarg2\fR? ?\fIargN\&.\&.\&.\fR?
.sp
\fB::defer::with\fR \fIvariableList\fR \fIscript\fR
.sp
\fB::defer::autowith\fR \fIscript\fR
.sp
\fB::defer::cancel\fR ?\fIid\&.\&.\&.\fR?
.sp
.BE
.SH DESCRIPTION
The \fBdefer\fR commands allow a developer to schedule actions to happen
as part of the current variable scope terminating\&.  This is most useful
for dealing with cleanup activities\&.  Since the defered actions always
execute, and always execute in the reverse order from which the defer
statements themselves execute, the programmer can schedule the cleanup
of a resource (for example, a channel) as soon as that resource is
acquired\&.  Then, later if the procedure or lambda ends, either due to
an error, or an explicit return, the cleanup of that resource will
always occur\&.
.PP
.SH COMMANDS
.TP
\fB::defer::defer\fR ?\fIcommand\fR? ?\fIarg1\fR? ?\fIarg2\fR? ?\fIargN\&.\&.\&.\fR?
Defers execution of some code until the current variable scope
ends\&.  Each argument is concatencated together to form the script
to execute at deferal time\&.
Multiple defer statements may be used, they are executed in the order
of last-in, first-out\&.
The return value is an identifier which can be used later with
\fBdefer::cancel\fR
.TP
\fB::defer::with\fR \fIvariableList\fR \fIscript\fR
Defers execution of a script while copying the current value of some
variables, whose names specified in \fIvariableList\fR, into the script\&.
The script acts like a lambda but executes at the same level as the
\fBdefer::with\fR
call\&.
The return value is the same as
\fB::defer::defer\fR
.TP
\fB::defer::autowith\fR \fIscript\fR
The same as
\fB::defer::with\fR but uses all local variables in the variable list\&.
.TP
\fB::defer::cancel\fR ?\fIid\&.\&.\&.\fR?
Cancels the execution of a defered action\&.  The \fIid\fR argument is the
identifier returned by
\fB::defer::defer\fR,
\fB::defer::with\fR, or
\fB::defer::autowith\fR\&.
Any number of arguments may be supplied, and all of the IDs supplied
will be cancelled\&.
.PP
.SH EXAMPLES
.CS


	package require defer 1
	apply {{} {
		set fd [open /dev/null]
		defer::defer close $fd
	}}

.CE
.SH REFERENCES
.IP [1]
.PP
.SH AUTHORS
Roy Keene
.SH "BUGS, IDEAS, FEEDBACK"
This document, and the package it describes, will undoubtedly contain
bugs and other problems\&.
Please report such in the category \fIdefer\fR of the
\fITcllib Trackers\fR [http://core\&.tcl\&.tk/tcllib/reportlist]\&.
Please also report any ideas for enhancements you may have for either
package and/or documentation\&.
.PP
When proposing code changes, please provide \fIunified diffs\fR,
i\&.e the output of \fBdiff -u\fR\&.
.PP
Note further that \fIattachments\fR are strongly preferred over
inlined patches\&. Attachments can be made by going to the \fBEdit\fR
form of the ticket immediately after its creation, and then using the
left-most button in the secondary navigation bar\&.
.SH KEYWORDS
cleanup, golang
.SH CATEGORY
Utility
.SH COPYRIGHT
.nf
Copyright (c) 2017, Roy Keene

.fi