You said: "short answer for why is that m// is a different command compared to m//g".

I was noting the similarity between these forms: 

my $foo="regexp";
my @matches = $foo =~ /(re)ge(xp)/;

#and

my $regex=qr{(re)ge(xp)};
my @matches = $foo =~ $regex;

[download]
In both of the above, "@matches" will get 2 entries "re" and "xp". I find it unfortunate that if your regexp was doubled, there is no way to directly use qr w/'g' i.e. one must use the m{} or // type form as in: 
> perl -we'use strict;use P;
my $regex=qr{(re)ge(xp)};
my @matches0 = "regexpregexp" =~ /(re)ge(xp)/g;
my @matches = "regexpregexp" =~ $regex;
my @matches1 = "regexpregexp" =~ /$regex/g;
P "matches=%s, 0=%s, 1=%s", \@matches, \@matches0, \@matches1; 
'
matches=["re", "xp"], 0=["re", "xp", "re", "xp"], 1=["re", "xp", "re",
+ "xp"]

[download]

In reply to Re^2: 'g' flag with 'qr' (different commands) (updated) by perl-diddler
in thread 'g' flag w/'qr' by perl-diddler

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