I am tried to get to work GNU Globals in my Emacs, and found that it is couldn't find a function definitions. After a long searching I end up that GNU Globals itself just somehow broken for me, it doesn't index almost anything! Consider an example:
$ cat test.cpp
class Foo {
public:
int myint;
short myshort;
char mychar;
};
int main() {
Foo obj;
obj.myint = 0;
return 0;
}
$ gtags
$ global Foo
test.cpp
$ global myint
$ global -r myint
$ global Foo::myint
$ global -r Foo::myint
$ cat GTAGS | grep myint
In the end I tried to grep «myint» and found that it isn't even present in GTAGS! The only place where it is mentioned is a GSYMS file. Of course, at first I tried the same code with a separate «.hpp» file, it didn't worked either.
UPDATE: I found that it is possible to create Global Tags with both of ctags and etags. For that it is need to issue export GTAGSLABEL=/usr/bin/etags (or to ctags), and launch gtags again. The variable works, it is easy to check by adding there a wrong path, so gtags would say about an error. So, I tried with my example the both backends, and neither worked.
Related
I am trying to understand this code in Perl that I have inherited:
sub myfunc($)
{
my ($path) = #_;
unless ($^C)
{
# manipulate path
}
return $path;
}
But I do not understand the $^C test. What does it do?
Perl's -c switch compiles the source and tells you if the syntax is valid. However, Perl doesn't have a strict separation between compile-time and run-time. You can run some code during the compilation (BEGIN blocks), and you can compile code when you are running (eval()).
This means that you might think that you are safe while syntax checking, and that you would be wrong. The second example actually runs some code:
$ perl -c -le 'print "Hello!"'
-e syntax OK
$ perl -c -le 'BEGIN{print "Hello!"}'
Hello!
-e syntax OK
This is more important in IDEs. Many of these will continually run perl -c on your source so it can highlight problems. However, this also means that your IDE is now potentially a trojan horse for executing that code you just copied and pasted from Stackoverflow.
Thus, the $^C guard (see perlvar):
$ perl -c -le 'BEGIN{ print "Hello!" unless $^C }'
-e syntax OK
I'm guessing that the developer who put that there either had a bet to use all the special variables in one program, or was reacting to unwanted behavior from their tools.
Is it possible to remove an entry from #INC from the command line?
I know export PERL5LIB=/path/file.pm can be used to add them, but can they be removed in a similar fashion?
EDIT:
I know that directories are not typically removed from #INC, but in my case (and maybe yours, if you are here for help) I added an entry of my own that I needed removed not only because it was a custom entry, but also because it specified a file (incorrect usage of #INC) and not a folder.
Additional Info:
The export command was executed from the command line, not from a script.
You could use the no lib pragma from the command line with perl -M-lib=...:
$ PERL5LIB=/tmp/foo perl -le 'print for #INC'
/tmp/foo
... normal #INC entries ...
$ PERL5LIB=/tmp/foo perl -M-lib=/tmp/foo -le 'print for #INC'
... normal #INC entries ...
Update: Based on the wording of the question, I assumed that you had a system where you had set PERL5LIB, and were asking how to exclude entries once in a while, only for specific runs of perl ("from the command line"). That's what the above does: The effect of no lib used on the command line is only temporary for that run of perl.
But the discussion in the comments revealed that it was the opposite: you had run export PERL5LIB=... "from the command line" (the effect of which is only temporary the current session/shell), and wanted to undo that change - for which the solution is either to run export PERL5LIB= (setting a new value overwrites the previous one, export is not like adding elements to a list, it just sets a new value), or to simply log out and back in again.
If you had set PERL5LIB in a place like the .profile or .bashrc files, then you would need to edit those and comment out or delete the entries you don't want, and log out and back in again.
You can change it in a BEGIN block. Example:
$ perl -MData::Dumper -e 'BEGIN { #INC = qw// }; print Dumper(\#INC);'
$VAR1 = [];
I would like to execute two or more commands back to back . But these commands are stored in a variable in my script. For example,
var="/usr/bin/ls ; pwd ; pooladm -d; pooladm -e"
The problem arises when I execute this variable via my script.
Suppose I go:
#!/bin/ksh -p
..
..
var="/usr/bin/ls ; pwd;pooladm -d; pooladm -e"
..
..
$var # DOES NOT WORK ..BUT WORKS WITH EVAL
It doesn't work ..
But the moment I use eval :
eval $var
It works brilliantly.
I was just wondering if there is any other way to execute a bunch of commands stored in a variable without using eval.
Also , Is eval usage considered a bad programming practice because my coding standards appear to shun its usage than embrace it . Please do let me know.
Remember that the shell only parses the line once. So when you expand your $var, it becomes one string containing blanks. Since you have no executable named '/usr/bin/ls ; pwd;pooladm -d; pooladm -e', it can't run it.
On the other hand, eval takes its arguments are re-scans them, now you get '/usr/bin/ls', 'pwd', and so on. It works.
eval is a little chancy because it leaves a possible security hole -- consider if someone managed to get 'rm -rf /' into the string. But it's a useful tool.
Use backticks and echo. In your case
`echo $var`
You could invoke another copy of the shell to run the command:
sh -c "$var"
This isn't necessarily better than using eval. The main practical difference is that eval will run the commands in the context of the current shell, while "sh -c" runs the commands in a separate shell instance. If var contains commands to set environment variables or change the current directory, you or may not want those commands to affect the current shell.
If you could explain the flow and how/why we can create a module to run with -Mm it will be helpful
-Mfoo simply generates the code use foo; and places it at the beginning of the code to be compiled.
-mfoo generates use foo ();
-Mfoo=bar,baz generates use foo ('bar','baz'); and so does -mfoo=bar,baz -- that is, there stops being a difference between -M and -m when you use the form with an equal sign, but without it, -m generates the "non-import" form of use.
This is all documented in perlrun.
I am unable to evaluate 'modern Perl' code inside the Perl debugger. It works OK when debugging the code in a file, but not from the prompt.
Minimal example:
# Activating 5-10 features with -E (it works)
$ perl -E 'say "x"'
x
# Calling the debugger with -E
# It works for infile code, but for prompt line code...
$ perl -dEbug Loading DB routines from perl5db.pl version 1.33
DB say "x"
String found where operator expected at (eval 16)[/local-perl/lib/5.12.1/perl5db.pl:638] line 2, near "say "x""
at (eval 16)[/local-perl/lib/5.12.1/perl5db.pl:638] line 2
eval '($#, $!, $^E, $,, $/, $\\, $^W) = #saved;package main; $^D = $^D | $DB::db_stop;say "x";
(Note: the same happens with "use feature ':5.10'".)
Am I missing something?
I found a reference to the issue here, but it's about a year old. However, the relevant portion of the Perl source hasn't changed since and can be seen here. Essentially, if you take a look at toke.c in the Perl source, you see the following:
if (PL_perldb) {
/* Generate a string of Perl code to load the debugger.
* If PERL5DB is set, it will return the contents of that,
* otherwise a compile-time require of perl5db.pl. */
const char * const pdb = PerlEnv_getenv("PERL5DB");
...
}
...
if (PL_minus_E)
sv_catpvs(PL_linestr,
"use feature ':5." STRINGIFY(PERL_VERSION) "';");
Basically, the debugger is loaded before the -E flag is processed, so the features aren't yet enabled when the debugger gets loaded. The gist of this is that you can't currently use -E with the -d command. If you want to use say, switch, or any other feature from the debug prompt, you have to do it like this:
DB<1> use feature 'say'; say "x"
x
The closest I've seen to a solution is:
copy perl5db.pl from your PERL5LIB to either somewhere in PERL5LIB or the current directory, with a different name, say myperl5db.pl
2. Edit myperl5db.pl to have use feature ':5.10'; (or just 'state', or just 'say') on the first line.
3. Set the environment variable PERL5DB to "BEGIN { require 'myperl5db.pl' }"
Which I found at PerlMonks.