Re^4: slow startup for some common modules? (autodie, Pod::Usage, Getopt::Long))

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Re^5: slow startup for some common modules? (autodie, Pod::Usage, Getopt::Long)) by LanX (Saint) on Jan 07, 2023 at 02:46 UTC
> use Pod::Usage if $needPod; Timing! You can't make a compile-time `use` (the BEGIN-part) depend on run-time conditions. FWIW: you could `use` the `if` pragma, but only if the condition is available at compile-time Because `use` takes effect at compile time, it doesn't respect the ordinary flow control of the code being compiled. In particular, putting a use inside the false branch of a conditional doesn't prevent it from being processed. If a module or pragma only needs to be loaded conditionally, this can be done using the `if` pragma: `use if $] < 5.008, "utf8"; use if WANT_WARNINGS, warnings => qw(all);` [download] but as you see the conditions here are (compile time) constants Cheers Rolf _{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l]

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Re^5: slow startup for some common modules? (autodie, Pod::Usage, Getopt::Long))
by LanX (Saint) on Jan 07, 2023 at 02:46 UTC

> use Pod::Usage if $needPod;

Timing! You can't make a compile-time use (the BEGIN-part) depend on run-time conditions.

FWIW: you could use the if pragma, but only if the condition is available at compile-time

Because use takes effect at compile time, it doesn't respect the ordinary flow control of the code being compiled. In particular, putting a use inside the false branch of a conditional doesn't prevent it from being processed. If a module or pragma only needs to be loaded conditionally, this can be done using the if pragma:

use if $] < 5.008, "utf8"; use if WANT_WARNINGS, warnings => qw(all);
[download]

but as you see the conditions here are (compile time) constants

Cheers Rolf
_{(addicted to the 𐍀𐌴𐍂𐌻 Programming Language :)

Wikisyntax for the Monastery}

[reply]
[d/l]