A question about the perl interp.

[Chad]

Give the following....
[cdalten@localhost oakland]$ more hello.pl
sub hello() {
print "hello \n";
}

hello();

I change the file permissions to read/write and then run the program..

[cdalten@localhost oakland]$ ls -al hello.pl
-rw------- 1 cdalten cdalten 48 Jul 12 15:11 hello.pl
[cdalten@localhost oakland]$ perl hello.pl
hello
[cdalten@localhost oakland]$

I'm assuming the perl interpreter reads in the hello.pl file. The
question is, how does it run hello(); if the actual function
definition is above the function itself. Does it just backtrack along
the text file and then re-read the actual function definition itself?

 

[Uri Guttman]

C> sub hello() {
C> print "hello \n";
C> }

C> hello();

C> I'm assuming the perl interpreter reads in the hello.pl file. The
C> question is, how does it run hello(); if the actual function
C> definition is above the function itself. Does it just backtrack along
C> the text file and then re-read the actual function definition itself?

perl first compiles the source code to an internal form and then runs
it. it isn't a true interpreter like the shell. note that if you didn't
call hello with () and it was called before its definition it would barf
an error. the () tells perl that you are calling a sub (unless the name
is a builtin). without the () it will think it is a bareword which isn't
legal under strict.

uri