Re: Why does Capture::Tiny require loading via BEGIN to successfully function?

[Anonymous Monk]

I disagree that this module's code is straightforward. I couldn't actually find the capture sub in that module at a glance -- the author redefines *_debug at run time, for instance, which hints at the possibility for obfuscation-like complexity).

However, what appears to be happening is that it's doing something to change parsing rules at compile time. This can be done with a function prototype, like sub foo (&) {}, which is how you create functions that act like builtins such as map and grep.

What this means is that when you require it at run time, that compile-time code isn't executed, so the magic of capture BLOCK isn't applied. Instead, you need to use capture( CODEREF ).

Look at this:

# perl -lwE "use Capture::Tiny (); say 'captured: ', Capture::Tiny::ca
+pture { say 'foo'  }"
captured: foo

# perl -lwE "require Capture::Tiny; say 'captured: ', Capture::Tiny::c
+apture { say 'foo' }"
foo
Can't call method "Capture::Tiny::capture" without a package or object
+ reference at -e line 1.

# perl -lwE "require Capture::Tiny; say 'captured: ', Capture::Tiny::c
+apture(sub { say 'foo' })"
captured: foo

Upshot: without the compile-time-added syntax sugar, you need to call this sub like capture($coderef);.