Perl: precedence (Leftward list operator) -

from programming perl pg 90, says:

   @ary = (1, 3, sort 4, 2);     print @ary; 

the commas on right of sort evaluated before sort commas on left evaluated after. ... list operators tend gobble .. , act simple term"

1. does assignment result in sort being processed or happen when @ary expanded print?
2. what mean "comma" stuff?? understanding in assignment statement, comma has lower priority list operator therefore sort runs first , gobbles it's arguments (4 , 2).. how heck comma being evaluated @ all?? statemnent becomes (1, 3, 2, 4) list assigned.. comma acting list separator , not operator!! in fact on pg:108 says: not confuse scalar context use of comma list context use..

3. what leftward , rightward list operator? print @ary rightward list operator?? has low priority?

   print($foo, exit);

here, how precedence evaluated? print list operator looks function should run first! has 2 arguments $foo , exit.. why exit not treated string??? after priority-wise print(the list operator) has higher priority??

print $foo, exit; 

here, have print , , operators list operator has higher precedence.. so.. exit should treated string - why not??

   print ($foo & 255) + 1, "\n"; 

here since it's list operator prints $foo & 255 shouldn't similar happen above mentioned exit stuff..

when in doubt how perl parsing construct, can run code through b::deparse module, generate perl source code compiled internal representation. first example:

$ perl -mo=deparse,-p -e '@ary = (1, 3, sort 4, 2); print @ary;' (@ary = (1, 3, sort(4, 2))); print(@ary); -e syntax ok 

so can see, sort takes 2 arguments right.

as far execution order goes, can find out b::concise module (i've added comments):

$ perl -mo=concise,-exec -e '@ary = (1, 3, sort 4, 2); print @ary;' 1  <0> enter  2  <;> nextstate(main 1 -e:1) v:{ 3  <0> pushmark s       # start of list 4  <$> const[iv 1] s    # 1 added list 5  <$> const[iv 3] s    # 3 added list 6  <0> pushmark s       # start of sort's argument list 7  <$> const[iv 4] s    # 4 added sort's argument list 8  <$> const[iv 2] s    # 2 added sort's argument list 9  <@> sort lk          # sort run, , returns list outer list  <0> pushmark s b  <#> gv[*ary] s c  <1> rv2av[t2] lkrm*/1 d  <2> aassign[t3] vks/common  # list assigned array e  <;> nextstate(main 1 -e:1) v:{ f  <0> pushmark s         # start of print's argument list g  <#> gv[*ary] s         # array loaded print's argument list h  <1> rv2av[t5] lk/1  <@> print vk           # print outputs it's argument list j  <@> leave[1 ref] vkp/refc -e syntax ok 

for second example:

$ perl -mo=deparse,-p -e 'print $foo, exit;' print($foo, exit); -e syntax ok  $ perl -mo=concise,-exec -e 'print $foo, exit;' 1  <0> enter  2  <;> nextstate(main 1 -e:1) v:{ 3  <0> pushmark s 4  <#> gvsv[*foo] s   # add $foo argument list 5  <0> exit s         # call `exit` , add return value list 6  <@> print vk       # print list, never here 7  <@> leave[1 ref] vkp/refc -e syntax ok 

so can see, exit builtin run while trying assemble argument list print. since exit causes program quit, print command never gets run.

and last one:

$ perl -mo=deparse,-p -e 'print ($foo & 255) + 1, "\n";' ((print(($foo & 255)) + 1), '???');  # '???' means optimized away -e syntax ok  $ perl -mo=concise,-exec -e 'print ($foo & 255) + 1, "\n";' 1  <0> enter  2  <;> nextstate(main 1 -e:1) v:{ 3  <0> pushmark v 4  <0> pushmark s 5  <#> gvsv[*foo] s 6  <$> const[iv 255] s 7  <2> bit_and[t2] sk 8  <@> print sk 9  <$> const[iv 1] s  <2> add[t3] vk/2 b  <@> list vk c  <@> leave[1 ref] vkp/refc -e syntax ok