Re: how to call a sub via variable in library

I've been staring at this unholy construct $self->{&{\&{$testname}}}->($system); for about 15 minutes, And I still haven't a clue what it's meant to do.

Perhaps you could fill in the blanks?

$testname is a string containing the name of a subroutine?
\&{ $testname }; returns a code reference to the named subroutine.
&{ \&{ $testname } } invokes that coderef. Ie, a long winded and obfuscated way of doing: &$testname
$self->{ &{ \&{ $testname } } } Uses the (if any) return code from the subroutine as a key into the object hash.
$self->{ &{ \&{ $testname } } }->( ... ); who's associated value is another coderef, which it invokes ...
$self->{ &{ \&{ $testname } } }->( $system ); passing one variable $system (which is apparently a hashref.)

Unless you have pre-populated the object hash with a key matching every possible return value from every possible test name, and associated an appropriate coderef for all of those keys; that line isn't trying to do what you think it is. (And even if it is, the way it is written is unnecessarily complicated and obfuscate.)

(And a brief glance at the rest of your code makes me think you're writing code you will not be able to maintain.)

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Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

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Re^2: how to call a sub via variable in library by Anonymous Monk on Nov 17, 2014 at 19:33 UTC
I've been staring at this unholy construct $self->{&{\&{$testname}}}->($system); for about 15 minutes, And I still haven't a clue what it's meant to do. This is a very obscure and useless feature of Perl. Documented in strict `$bar = \&{'foo'}; &$bar;` [download] is allowed so that "goto &$AUTOLOAD" would not break under stricture.	[reply] [d/l]
Re^3: how to call a sub via variable in library by BrowserUk (Patriarch) on Nov 17, 2014 at 19:46 UTC
That bit is obfuscated, but at least understandable. It's the invoking of a subroutine from the object hash keyed by the return code of that subroutine that I find completely unlikely. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply]
Re^2: how to call a sub via variable in library by glenn (Scribe) on Nov 17, 2014 at 21:18 UTC
you have given the best understanding of which i did not even have... Although this is wrong here is what i want to accomplish: $self->&$testname($system). Execute sub '$testname' with '$system' as parameter in object '$self'. Could you help further with this???	[reply]
Re^3: how to call a sub via variable in library by BrowserUk (Patriarch) on Nov 17, 2014 at 22:04 UTC
here is what i want to accomplish: $self->&$testname($system). Execute sub '$testname' with '$system' as parameter in object '$self'. Depends what do you mean by "... in object $self"? I see two possible interpretations of that: You simply want to execute the sub named in `$testname` (whilst incidentally running inside a method of object `$self`); in which case all you need is: `$testname->( $system );` [download] You'll probably need `no strict 'refs';` for that. Alternatively, you might mean that you want to invoke the method of object `$self`, who's name is held in `$testname`; in which case all you need is: `$self->$testname( $system );` [download] Seems to work fine with full strict. With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice.	[reply] [d/l] [select]


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