Re: "Can't return a temporary from lvalue subroutine..."



Anno Siegel wrote:

I suppose your motivation is that you like the idea of lvalue methods,
but need more control over what gets stored by careless users in your
sensitive objects.  A similar problem exists with objects that expose
(parts of) their interior though overloading a dereference operator,
say %{}.  Like lvalues, it gives you pretty syntax, but leaves your
objects wide open.  I have used tied hashes to correct this (that is,
returned a reference to a tied hash in response to %{ $obj}, and haven't
encountered the particular difficulty you're seeing.  That may be
an alternative approach.


Here be dragons.

There are bugs in Perl. In particular if the reference returned by the %{} overload is the only reference to the tied hash some very nasty things happen very soon. Even if it's not, nasty things seem to happen after a while.

I wrote whole load of in-house classes that used this API technique and then had to labourously go through all our programs to use a direct method-call API rather than the overload-tie API.
.

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