[fpc-devel] Local procedures as procedural parameter

Florian Klaempfl florian at freepascal.org
Mon Mar 14 08:39:53 CET 2005

Adriaan van Os wrote:

> 1. On the todo list for fpc's MacPas mode is a feature that allows local 
> procedures (functions) to be passed a procedural parameters. I 
> tentatively put it on my own todo list, since this is the feature that I 
> like most in Pascal compilers, at the same time making a small 
> contribution to fpc and learning about the compiler. Before doing so, I 
> need agreement on the method followed.

If I'd to rate this task on a scale from 0 (easy) to 5 (hard) I would give it a 
   4 :)

This is because, as Peter mentioned, parsing and type checking of proc. vars is 
really hard and messy. The reason is that proc var expressions are undefined 
without context and that's why fpc mode requires @ or () to define exactly 
what's meant if a proc. var or proc name is found.

> Note that, with this solution, typed procedural variables can be passed 
> as actual procedural parameters to "iso" style formal parameters, but 
> not the other way round.

How are variables of this type declared?

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