Conventions for %w, %W, %q, %Q, etc. about ruby-style-guide

[mitio]

@burke, I would mostly agree with you.

I got some stats from the Rails repo I have locally and you can see the results below. I sure think that the lack of convention for the % literals is not a healthy thing for larger projects and would vote for the guide to include some hints about their usage. Provided we could settle on something... :)

Rails master stats for %{ vs %( vs %[:

• grep -rI '%{' . | wc -l: 472
• grep -rI '%(' . | wc -l: 1046
• grep -rI '%\[' . | wc -l: 2

Rails master stats for %w{ vs %w( vs %w[:

• grep -rI '%w{' . | wc -l: 43
• grep -rI '%w(' . | wc -l: 556
• grep -rI '%w\[' . | wc -l: 24

[jibiel]

Sorry for the gravedigging, but what's your opinion on contexts like this one:

add_index :thingies, [:category_id, :property], unique: true
add_index :thingies, %i{category_id property}, unique: true

I think the second example loses in readability and this is obvious exception to the rule, since code like this rarely changes and the provided examples (types / states / roles) show only one side of the coin: ease of adding/removing items.

[DAddYE]

I agree with you, especially, what is better

%w(foo bar)
%w{foo bar}
%w[foo bar]

In this example I saw second version, but sometimes also third, when Im working with Enums, I prefer to enclose it into [] ie: %w[one two] when it returns strings or some thing like that I prefer second one i.e.: %r{my/regex}

[mitio]

I guess these should be avoided as much as possible, but when I use them:

• %w[foo bar baz] — here I prefer the [] brackets to associate the list more closely with an array, what it is a literal form of. And usually I try to avoid this construct.
• %{complex strings} — I use this for complex and usually multiline strings because I find it easier to read than to have escaped quotes in the string. However, one should ask himself if this "complex" string really needs to be embedded in the code. It surely smells a bit.

These are probably the only two versions of the %-notion I've ever used in practice.

I sure prefer the /regex\/pattern/ syntax for defining regular expressions. Then again, I don't recall writing awfully complex regexes and probably I've never felt the need to use %r{regex/pattern}.

[DAddYE]

100% agree with you, I avoid using of %{complex string} and instead I use (especially for multiline) this:

usage = <<-PLAIN.gsub(/ {2}/, '')
  ===== EXAMPLE ======
  Here some text
  explain cmd usage
  ====================
PLAIN
puts usage

[burke]

I think in general:

• Use %w freely.
• Use %r for regular expressions matching more than one '/' character.
• Avoid %q, %Q, %x, %s, and %W.
• Use {} for delimiters.

Most code I see uses {}. I guess the question is whether this guide should be prescriptive or descriptive? [] makes sense for the %w syntax, but isn't used as often.

EDIT: I could be convinced on the %q point, but I've never felt a need for it.

[burke]

I just skimmed Rails' use of %(), and I'm now convinced it's actually a great pattern. See:

table << %(<tr><td class="name">#{CGI.escapeHTML(name.to_s)}</td>)

I feel like if this were more documented and encouraged, it would be a great thing.

How about this:

• Use %w freely, with () delimiters.
• Use %() for single-line strings requiring both interpolation and embedded double-quotes. For multi-line strings, prefer heredocs.
• Use %r for regular expressions matching more than one '/' character. Use {} for delimiters, to avoid having to escape capture groups.
• Avoid %q, %Q, %x, %s, and %W.

[bbatsov]

I like it. We just need a couple of examples illustrating good and bad style :-) I sense a pull request coming in ( or should I right some examples myself ) ;-)

[mitio]

@burke, note that when using the % literal with {, [ or (, you don't need to escape any {, [ or ( in your string or regexp, provided they have a matching close symbol.

For example, the following examples work:

# prints out 123
puts $1 if %r(some(\d+)text) =~ "some123text"

# evaluates to "this is a function() in a string"
%(this is a function() in a string)

[burke]

@mitio Oh, that's interesting. I'm putting together a section on percent functions right now; I'll use () for %r too. If anyone wants to change that later, I'm okay with.