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.IX Title "Object::Pad::FieldAttr::Trigger 3pm"
.TH Object::Pad::FieldAttr::Trigger 3pm 2024-03-07 "perl v5.38.2" "User Contributed Perl Documentation"
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.SH NAME
"Object::Pad::FieldAttr::Trigger" \- invoke an instance method after a ":writer" accessor
.SH SYNOPSIS
.IX Header "SYNOPSIS"
.Vb 2
\&   use Object::Pad;
\&   use Object::Pad::FieldAttr::Trigger;
\&
\&   class Label {
\&      field $title :param :reader :writer :Trigger(redraw);
\&
\&      method redraw {
\&         ...
\&      }
\&   }
\&
\&   my $label = Label\->new( text => "Something" );
\&
\&   $label\->set_label( "New text here" );
\&   # $label\->redraw is automatically invoked
.Ve
.SH DESCRIPTION
.IX Header "DESCRIPTION"
This module provides a third-party field attribute for Object::Pad\-based
classes, which declares that a named instance method shall be invoked after
a generated \f(CW\*(C`:writer\*(C'\fR accessor method is called.
.PP
\&\fBWARNING\fR The ability for Object::Pad to take third-party field attributes
is still new and highly experimental, and subject to much API change in
future. As a result, this module should be considered equally experimental.
.SH "FIELD ATTRIBUTES"
.IX Header "FIELD ATTRIBUTES"
.SS :Trigger
.IX Subsection ":Trigger"
.Vb 1
\&   field $name :writer :Trigger(NAME) ...;
.Ve
.PP
Declares that the accessor method generated for the field by the \f(CW\*(C`:writer\*(C'\fR
attribute will invoke the method named by the \f(CW\*(C`:Trigger\*(C'\fR attribute, after the
new value has been stored into the field itself. This method is invoked with
no additional arguments, in void context.
.PP
Note that this only applies to the generated accessor method. It does not
apply to direct modifications of the field variable by method code within the
class itself.
.SH AUTHOR
.IX Header "AUTHOR"
Paul Evans <leonerd@leonerd.org.uk>