[Koha-bugs] [Bug 11998] Syspref caching issues

[bugzilla-daemon at bugs.koha-community.org]

http://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=11998

--- Comment #32 from Robin Sheat <robin at catalyst.net.nz> ---
(In reply to Jonathan Druart from comment #30)
> Created attachment 33183 [details] [review]
> Bug 11998: QA follow-up - fix the perlcritic error
> 
> % perlcritic C4/Context.pm
> Variable declared in conditional statement at line 544, column 5.
> Declare variables outside of the condition.  (Severity: 5)

So I was wondering what purpose this change solves, turns out it can be
important:

<grantm> my $var if condition    is a messy construct that doesn't do quite
what you expect
<grantm> if condition is true, then $var is created in the current scope and
gets cleaned up when the scope ends
<grantm> but if condition is not true, then $var does not get created at
runtime and instead, the $var that was inferred at compile time is used instead
<grantm> it ends up being a file-scoped global that persists a value
<Ned> ahh
<Ned> that's a bit of a nasty side-effect :p
<grantm> actually, it's not a file-scoped global
<grantm> it's a lexical and the sub is a closure over that lexical
<grantm> the thing about 'my' is that it has compile-time and run-time effects
and in this instance the run-time effects only get to happen if condition is
true
<grantm> historical note: this bug/feature was how people used to do state
variables before the 'state' keyword existed
<Ned> heh
<grantm> specifically: my $state_variable = 0 if 0;
<Ned> there should be a word for that
<Ned> "fug" perhaps
<grantm> it's certainly fugly

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