Beefy Boxes and Bandwidth Generously Provided by pair Networks
Keep It Simple, Stupid
 
PerlMonks  

comment on

( [id://3333]=superdoc: print w/replies, xml ) Need Help??

It's worth noting, by the way, that using $foo != 7 as the control statement in an if statement is generally a Bad Idea. The unless statement is designed to cover that need, and using the != operator there just makes the code harder to read later when it must be maintained.

I second DrHyde (Re^3: if variants). It's definately not bad and neither is it a maintenance trouble. That whole sentence above should be removed from your text. It's just plain wrong.

The unless keyword is made to make you write code more like a natural language. It's not there to take !='s place in if expressions. They can both coexist happily and be mixed however you please.

Why the combination of unless and else is shunned by many is because it's a sort of double negation.

if (X) { ... } else { ... }
can be read
if (X) { ... } if (not X) { ... }
"unless X" can be read "if not X". Combining this gives you
unless (X) { ... } else { ... } if (not X) { ... } if (not not X) { ... }
which just doesn't read well. Logically it's not strange but it's a funny and inappreciated way of expressing oneself.

My own (rather inconsistent) style is to use unless for exceptional behaviour, and if for expected/wanted behaviour. When using unless I usually want something, but something might stop me from doing that. With if I express that I perhaps want something, perhaps not.

print ... unless $quiet; # I want to print. exit if $done; # I might want to exit here. exit unless $stay; # I want to exit here, but apparently # something is holding me back.
The examples can perhaps be better, and I'm not consistant myself in my use, but that's give you an idea of how I tend to use them.

ihb

See perltoc if you don't know which perldoc to read!
Read argumentation in its context!


In reply to Re^3: if variants by ihb
in thread if variants by apotheon

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post; it's "PerlMonks-approved HTML":



  • Are you posting in the right place? Check out Where do I post X? to know for sure.
  • Posts may use any of the Perl Monks Approved HTML tags. Currently these include the following:
    <code> <a> <b> <big> <blockquote> <br /> <dd> <dl> <dt> <em> <font> <h1> <h2> <h3> <h4> <h5> <h6> <hr /> <i> <li> <nbsp> <ol> <p> <small> <strike> <strong> <sub> <sup> <table> <td> <th> <tr> <tt> <u> <ul>
  • Snippets of code should be wrapped in <code> tags not <pre> tags. In fact, <pre> tags should generally be avoided. If they must be used, extreme care should be taken to ensure that their contents do not have long lines (<70 chars), in order to prevent horizontal scrolling (and possible janitor intervention).
  • Want more info? How to link or How to display code and escape characters are good places to start.
Log In?
Username:
Password:

What's my password?
Create A New User
Domain Nodelet?
Chatterbox?
and the web crawler heard nothing...

How do I use this?Last hourOther CB clients
Other Users?
Others goofing around in the Monastery: (4)
As of 2024-03-29 10:20 GMT
Sections?
Information?
Find Nodes?
Leftovers?
    Voting Booth?

    No recent polls found