The following script gives me what I want but Perl also throws me a warning saying "Useless use of a variable in void context". What does it mean?
use strict;
use warnings;
my $example = 'http\u003a//main\u002egslb\u002eku6\u002ecom/c0/q7LmJPfV4DfXeTYf/1260269522170/93456c39545857a15244971e35fba83a/1279582254980/v632/6/28/a14UAJ0CeSyi3UTEvBUyMuBxg\u002ef4v\u002chttp\u003a//main\u002egslb\u002eku6\u002ecom/c1/q7LmJPfV4DfXeTYf/1260269522170/3cb143612a0050335c0d44077a869fc0/1279582254980/v642/10/20/7xo2MJ4tTtiiTOUjEpCJaByg\u002ef4v\u002chttp\u003a//main\u002egslb\u002eku6\u002ecom/c2/q7LmJPfV4DfXeTYf/1260269522170/799955b45c8c32c955564ff9bc3259ea/1279582254980/v652/32/4/6pzkCf4iqTSUVElUA5A3PpMAoA\u002ef4v\u002chttp\u003a//main\u002egslb\u002eku6\u002ecom/c3/q7LmJPfV4DfXeTYf/1260269522170/cebbb619dc61b3eabcdb839d4c2a4402/1279582254980/v567/36/19/MBcbnWwkSJu46UoYCabpvArA\u002ef4v\u002chttp\u003a//main\u002egslb\u002eku6\u002ecom/c4/q7LmJPfV4DfXeTYf/1260269522170/1365c39355424974dbbe4ae8950f0e73/1279582254980/v575/17/15/EDczAa0GTjuhppapCLFjtaQ\u002ef4v';
my #raw_url = $example =~ m{(http\\u003a.+?f4v)}g;
my #processed_url = map {
s{\\u003a}{:}g,$_;
s{\\u002e}{.}g,$_;
s{\\u002d}{#}g,$_;
} #raw_url;
print join("\n",#processed_url);
And why this map thing doesn't work if I omit those dollar underscores like so?
my #processed_url = map {
s{\\u003a}{:}g;
s{\\u002e}{.}g;
s{\\u002d}{#}g;
} #raw_url;
When I omit those dollar underscores, I get nothing except for a possibly success flag "1". What am I missing? Any ideas? Thanks like always :)
What you want is...
my #processed_url = map {
s{\\u003a}{:}g;
s{\\u002e}{.}g;
s{\\u002d}{#}g;
$_;
} #raw_url;
A map block returns the value composed of the last statement evaluated as its result. Thats why we pass the $_ as the last statement. The substitution operator s{}{} returns the number of substitutions made.
In your prior setup, you had by itself the following statement. Which is pretty much meaningless and that is what Perl is warning about.
s{\\u003a}{:}g, $_;
You already have the answer you were looking for, but I wanted to point out a subtlety about using the substitution operator inside a map block: your original array is also being modified. If you want to preserve the original array, one way to do it is to make a copy of the array, then modify only the copy:
my #processed_url = #raw_url;
for (#processed_url) {
s{\\u003a}{:}g;
s{\\u002e}{.}g;
s{\\u002d}{#}g;
}
Or, if you only need one array, and you want the original to be modified:
for (#raw_url) {
s{\\u003a}{:}g;
s{\\u002e}{.}g;
s{\\u002d}{#}g;
}
Related
I have a bunch of scripts I wanted to replace some texts.
Context : We are using selenium for UI Automation. We used to store the references to the UiElements in a map. But we are now moving to use PageFactory (a class with all the UiElements declared as a string)
So when we used map, we had to call the UIelements as objectMap.getIdentifier("navigate.leftsidebar"). But now with PageFactory (its like instantiating a object, and the UIElements are declared as a string), I can access these UIelements objectPageFactory.navigate_leftsidebar (here navigate_leftsidebar is a String)
So I will need to go modify all my existing scripts. Is there a way I can write a script to get this replaced, than doing it manually ?
Below are the 3 scenarios that I will encounter :
Click(getElement(objectMap.getIdentifier("navigate.leftsidebar").replace("$Page", "Inbox")), "clicking on an element");
objectMap.getIdentifier("navigate.leftsidebar")
Click(objectMap.getIdentifier("navigate.leftsidebar"), "clicking on an element");
This is the expected output:
Click((objectPageFactory.navigate_leftsidebar("Inbox")), "clicking on an element");
objectPageFactory.navigate_leftsidebar
Click(objectPageFactory.navigate_leftsidebar, "clicking on an element");
Changes are :
"objectMap" to be renamed as "objectPageFactory"
There could be different types of map. if objectMap , it should be replaced as objectPageFactory; if loginMap, it should be changed as loginPageFactory
objectMap.getIdentifier("navigate.leftsidebar") >>>> objectFactory.navigate_leftsidebar (the String literal inside the bracket is separated by underscore instead of dots
getElement is not needed now
we used to have some dynamic UiElements (navigate.leftsidebar in this case), for which we used to call String.replace, now we are writing functions which will internally do a String.format
getElement(objectMap.getIdentifier("navigate.leftsidebar").replace("$Page", "Inbox")) >>>>> objectPageFactory.navigate_leftsidebar("Inbox")
I got a perl script from this link, which will do partial job sed command to replace dots.
I just need to add the different scenarios to this, is there a way ? the output should now have a pageFactory text too, based on which map
#! /usr/bin/perl
use strict ;
sub fix { $_ = shift ; s/"//g ; s/\./_/g ; return $_ }
while ( <> ) {
s/getElement\(objectMap\.getIdentifier\(("?[a-z.]+"?)\)/fix($1)/e ;
s/objectMap\.getIdentifier\(("?[a-z.]+"?)\)/fix($1)/e ;
print
}
This seems to provide the output you requested. I don't understand the language you're changing, so there might be corner cases it processes wrong. Make a backup before you change the files!
#!/usr/bin/perl
use warnings;
use strict;
sub fix {
my ($id) = #_;
return $id =~ s/[.]/_/gr
}
while (<>) {
s{getElement\((object|login)Map\.getIdentifier\("([^"]*)"\)\.replace\("\$Page", "([^"]*)"\)\)}
{"$1PageFactory." . fix($2) . qq(("$3"))}ge;
s{(object|login)Map\.getIdentifier\("([^"]*)"\)}
{"$1PageFactory." . fix($2)}ge;
print;
}
Question Updated
I have list of (few more) regex patterns like: (Note: Sequence is very Important)
([a-z]+)(\d+)
\}([a-z]+)
([a-z]+)(\+|\-)
([0-9])\](\+|\-)
...
...
my input file like :
\ce{CO2}
\ce{2CO}
\ce{H2O}
\ce{Sb2O3}
...
...
In my code I am finding the each and every regex patterns like
if($string=~m/([a-z]+)(\d+)/g) { my statements ... }
if($string=~m/\}([a-z]+)/g) { my statements ... }
if($string=~m/([a-z]+)(\+|\-)/g) { my statements ... }
if($string=~m/([0-9])\](\+|\-)/g) { my statements ... }
Instead of doing the above code Is there any other way to simplify the code?
Could you someone please share your thoughts for my improvement for better coding.
Disclaimer: Your question is very hard to read, so this is pretty much guesswork. I am not sure I understand what you want to do.
When you are processing data in a dynamic way, a typical approach is to use a dispatch table. We can do something similar here. Often a hash or hash reference is used for that, but since we want a specific order, I will be using an array instead.
my #dispatch = (
{
pattern => qr/f(o)(o)/,
callback => sub {
my ($one, $two) = #_;
print "Found $one and $two\n";
},
},
{
pattern => qr/(bar)/,
callback => sub {
my $capture = shift;
print "Saw $capture";
},
},
);
This basically is a list of search patterns and associated instructions. Each pattern has a callback, which is a code reference. I decided it would make sense to pass in the capture variables, because your patterns have capture groups.
Now in order to call them, we iterate over the dispatch array, match the pattern and then call the associated callback, passing in all the captures.
my $text = "Foo bar foo bar baz.";
foreach my $search (#dispatch) {
if ($text =~ $search->{pattern}) {
$search->{callback}->(#{^CAPTURE}); # this requires Perl 5.26
}
}
Please note that I am using #{^CAPTURE}, which was added to Perl in version 5.25.7, so you would require at least the stable Perl 5.26 release to use it. (On an older Perl, my #capture = $t =~ $search->{pattern} and $search->{callback}->(#capture) will behave similarly).
This is way more elegant than having a list of if () {} statement because it's very easy to extend. The dispatch table could be created on the fly, based on some input, or entirely read from disk.
When we run this code, it creates the following output
Found o and o
Saw bar
This is not very spectacular, but you should be able to adapt it to your patterns. On the other hand I don't know what you are actually trying to do. If you wanted to modify the string instead of only matching, you might need additional arguments for your callbacks.
If you want to learn more about dispatch tables, I suggest you read the second chapter of Mark Jason Dominus' excellent book Higher Order Perl, which is available for free as a PDF on his website.
Your question is hard to read, mainly because you have the /g at the end of your regex searches (which returns a list), however, you only check if it matches once.
I'm making the following assumptions
All matches are required
the code can be a single or double match
both groups captured in one line
i think you want
while ( $string =~ /(([a-z]+)(\d+)|\}([a-z]+)|([a-z]+)(\+|\-)|([0-9])\](\+|\-))/g )
{
#$1 has the whole match
#$2 has the first group if defined
#$3 has the second group if defined
}
However, I prefer the method below. this will capture in one line
while ($string =~ /([a-z]+\d+|\}[a-z]+|[a-z]+\+|\-|[0-9]\]\+|\-)/g )
{
# in here split the match if required
}
I recommend you use regex comments to make this clearer.
if you just want a single match, use
if(
$string=~m/([a-z]+)(\d+)/ ||
$string=~m/\}([a-z]+)/ ||
$string=~m/([a-z]+)(\+|\-)/ ||
$string=~m/([0-9])\](\+|\-)/
)
{
#some code
}
Am trying to make a subroutine that replaces data depending on datatype: the problem is i can't get the datatype of the parameter, i used this:
sub replace {
my ($search, $replacement, $subject) = #_;
if (ref($search) eq "HASH") {
print "r is a reference to a HASH.\n";
}
elsif (ref($search) eq "SCALAR") {
print "r is a reference to a SCALAR.\n";
}
elsif (ref($search) eq "ARRAY") {
print "r is a reference to a ARRAY.\n";
}
}
my $str = "Foo";
my #arr = ("Foo");
replace($str);
replace(#arr);
But none works. am really new to perl
ref() takes a reference to something, not the something itself. Here:
replace($str);
replace(#arr);
...you are sending in the something directly. Send in a reference to the something instead, by putting a \ in front of it (which says, "take a reference to this something"):
replace(\$str);
replace(\#arr);
Output:
r is a reference to a SCALAR.
r is a reference to a ARRAY.
Note also that in your replace() function, in this line:
my ($search, $replacement, $subject) = #_;
You are effectively asking for a scalar value as the thing to search, so passing in a list (array, hash etc) will clobber $replacement and $subject if the passed in list has more than one element, so you may want to do something like this to ensure you're getting the proper params, and nothing is clobbered unexpectedly:
sub replace {
my ($search, $replacement, $subject) = #_;
die "first arg must be a ref\n" if ! ref $search;
Of course, you can do further argument checking, but this'll ensure that the first parameter can only be a reference to something. Instead of die(), you can also just return so the program doesn't crash, or print or warn and then return.
It is not stated what you want to do with it, but here's what is wrong with what you show.
The ref function shows the datatype of the reference subtmitted to it, or it returns an empty string if its argument isn't a reference at all.
So to get the expected behavior you should do
replace(\$str);
replace(\#arr);
Also, you need to add the test to your function
else (not ref $search)
for when a submitted string is not a reference.
For completeness, I should also point out an issue, explained in the answer by stevieb. When you pass an array to a function, it receives it as a flat list of arguments. With your function you clearly do not want replace(#arr). They are assigned to your list of scalar variables in order, one element to each. (As soon as there is an array variable it all goes into it.) See, for example, this post.
I have .ini file (config file for the database operations):
[Section1]
SQL1=select * from <tablename>
SQL2=insert into table <table name>
I have written below code to read the each section of .ini file and its working perfect. I have to use below subroutine in my mail file, I want to call it and pass the each value in each section into the hash over there and do the database operations.
below is code:
sub Read_INI_files_get_initialData {
my ( %ini_file, $ini_sect );
tie %ini_file, 'IniFiles',( -file => "/home/testtool/config/InitialData.ini" );
for $ini_sect ( keys %ini_file ) {
%$ini_sect = %{ $ini_file{$ini_sect} };
}
print "$Section1{SQL1}\n"; # output prints the 1st SQL1 statement return in .ini file.
return (\%Section1);
}
When I call this subroutine from main file, I don't get any return value which I could use for further database opration.
You have a mixup with your variables. Also I'm not sure what you are trying to do. If you only want to read Section1, consider this example (which I have not tested).
use strict;
use warnings;
use feature 'say';
sub Read_INI_files_get_initialData {
tie my %ini_file, 'IniFiles',( -file => "/home/testtool/config/InitialData.ini" );
say "$ini_file{Section1}->{SQL1}";
# return a hashref
return { $ini_file{Section1} };
}
Basically what you did was the following:
for $ini_sect ( keys %ini_file ) {
%$ini_sect = %{ $ini_file{$ini_sect} };
}
print "$Section1{SQL1}\n"; # output prints the 1st SQL1 statement return in .ini file.
return (\%Section1);
The $ini_sect is declared above, but then you use it to iterate over the keys. So the first time the for is run, it will get a key of %ini_file. Now in the loop you asume it is actually a hashref, dereference it and assign another hash (which you dereferenced from a hash ref using the key). There are two issues here.
First, you are overwriting the variable that holds the key. In the next iteration, that value would be gone.
Second, and more important, you are trying to dereference a string. That won't work. If you add use strict and use warnings to you program (as I did above), it will tell you Can't use string ("Section1") as a HASH ref.... So there lies another problem.
What it will also tell you is that Global symbol "%Section1" requires explicit package name in the return, because you never declared it.
Think about what you want to do in your function. Use as many variables as you need, and give them meaningful names. Do you just want to read the first section of the file? Go ahead, reference it directly.
Do you want to make a copy of the whole thing? Maybe tie is not the best option. See Config::IniFiles how to do it with an OOp interface.
If I understand you correctly, you want to use the tied hash to access the SQL statements specified in your config file. This can be done by using the nested hash structure $ini_file{SectionName}{VariableName}:
use strict;
use warnings;
use Config::IniFiles;
my %initialData = Read_INI_files_get_initialData();
print $initialData{Section1}{SQL1} . "\n"; # Prints the Section1 SQL1 statement from .ini file.
sub Read_INI_files_get_initialData {
my %ini_file;
tie %ini_file, 'Config::IniFiles', ( -file => "InitialData.ini" );
return %ini_file;
}
In Perl, is it possible to arbitrarily end a map execution, e.g. something equivalent to last in a loop?
It would be a bit like this:
map {
if (test == true) { last; } dosomething
} #myarray
Nope. You can't last, next, etc. out of a map, grep or sort blocks because they are not loops.
Having said that, the code snippet in the question is poor practice because map should never be called in void context. They are supposed to be used to transform one list into another.
Here's a better way to write it if you really must inline it (modified after ysth's comment):
$_ == 10 && last, print for 1..15; # prints '123456789'
No. Use an ordinal foreach loop and the last statement.
Since 5.8.1, map is context aware - in void context, no lists are constructed.
Anyway, map is generally used to get a list from another list, evaluating expr for each element of the original list.
You could use a do-block with a for statement modifier:
do {
last if test;
dosomething;
} for (#myarray);
Though using a foreach block would probably be clearer, and future maintainers of your code will thank you.
foreach (#myarray) {
last if test;
dosomething;
}
You can use a long jump (eval/die pair) to bail out of any nested construct that doesn't directly support it:
eval { map{ die if test; dosomething } #myarray };
But as Zaid said, using a for/foreach loop in this case is better because you are not using the return value of map.
You want a for loop:
foreach ( #myarray ) {
last if test;
...
}
It does the same thing. map is for transforming one list into other lists.
There are map-like constructs that do exactly what you want to do. Take a look at List::Util and List::MoreUtils (conveniently also packaged together as List::AllUtils):
use List::MoreUtils 'first';
# get first element with a {foo} key
my $match = map { $_->{foo} eq 'some string' } #elements;
If you don't want to extract an element(s) from the list, then use foreach, as per the previous answers.
Try goto LABEL. However I do not know how safe is that.