[Pipet Users] Command Compilation in Piper: A Discourse

[Alexandre Fayolle]

On Tue, 13 Feb 2001, Jean-Marc Valin wrote:

> OK, there's two things here: internally, there's an abstract "Node"
> class, for which each new Node derives (as you see in the screenshot,
> "Constant", "Add" and "ExecStream" all derive from Node). Hovever,
> there's no need to discriminate between things that perform have the
> same function. A string is a string... regardless of whether you use it
> as a flag or a filename. If you look at C, for example, a (char *) or an
> int can be use for whatever you like.

True, but this is not the point. You can use void* pointers in C, instead
of char*. It"s just that sometimes it's nice to differentiate a char* and
a FILE*, for instance: the underlying representation _is_ a pointer (an
int ?), but the _semantics_ are different. 

The meaning of  a command line switch, a filename passed on the command
line, a keyword passed on the command line are different, even if they
are all thrown in char** argv when the program receives them. What Nicolas
meant is that if you give your program a bunch of arbitrary char*, it
won't be able to do much with it. Whereas if you say that this is a
switch, it should be followed by the name of an existing file, then it
becomes possible to process the data.
 
Alexandre Fayolle
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