Bug #11661
closedsprintf causes a KeyError instead of using a default value for hash substitution
Description
When using a format string that substitutes hash values (or using the %
operator on a string), instead of using the Hash's default value if a key is not present, it causes a KeyError.
As an end-user, to get around this, my hash needs to know about all the possible keys ahead of time and pre-assign a value to them or handle the KeyError. Logically, I would assume that the sprintf
implementation would use the default Hash value.
I wanted to open this issue to see what your collective thoughts were on this since I have a fork running locally that fixes this issue and was wondering if I could send a patch/PR for this.
This issue is reproducible using the following code:
my_hash = Hash.new('world')
puts "hello %{location}" % my_hash # expecting "hello world"
# "KeyError: key{location} not found"
Updated by nobu (Nobuyoshi Nakada) over 8 years ago
- Tracker changed from Bug to Feature
- Status changed from Open to Feedback
GH-1087 doesn't work properly with a default proc expecting an argument, but segfaults.
My patch.
diff --git i/sprintf.c w/sprintf.c
index 705d3ce..eee5695 100644
--- i/sprintf.c
+++ w/sprintf.c
@@ -605,13 +605,10 @@ rb_str_format(int argc, const VALUE *argv, VALUE fmt)
}
CHECKNAMEARG(start, len, enc);
get_hash(&hash, argc, argv);
- sym = rb_check_symbol_cstr(start + 1,
- len - 2 /* without parenthesis */,
- enc);
- if (sym != Qnil) nextvalue = rb_hash_lookup2(hash, sym, Qundef);
- if (nextvalue == Qundef) {
- rb_enc_raise(enc, rb_eKeyError, "key%.*s not found", len, start);
- }
+ sym = rb_cstr_intern(start + 1,
+ len - 2 /* without parenthesis */,
+ enc);
+ nextvalue = rb_hash_aref(hash, sym);
if (term == '}') goto format_s;
p++;
goto retry;
Updated by nobu (Nobuyoshi Nakada) over 8 years ago
- Status changed from Feedback to Assigned
Updated by nobu (Nobuyoshi Nakada) over 8 years ago
- Tracker changed from Feature to Bug
- Backport set to 2.0.0: REQUIRED, 2.1: REQUIRED, 2.2: REQUIRED
Updated by Hanmac (Hans Mackowiak) over 8 years ago
hm might it be possible that sprintf only uses default value/or default proc if the hash does has default,
but does still raise KeyError if it doesnt?
another idea would be that is does try to use hash[key] function if hash is a non-hash object.
(but that might reduce the calcing speed if not checked right)
Updated by eddyluten (Eddy Luten) over 8 years ago
Hans Mackowiak wrote:
hm might it be possible that sprintf only uses default value/or default proc if the hash does has default,
but does still raise KeyError if it doesnt?another idea would be that is does try to use hash[key] function if hash is a non-hash object.
(but that might reduce the calcing speed if not checked right)
Nobuyoshi Nakada: this was the change I initially made myself but couldn't get it to work properly with hash substitutions. Maybe I did something wrong in my testing, I will attempt to use your changes, thanks! :)
Hans Mackowiak: so raise KeyError is the default is nil
? I think that could work, since if you wanted empty strings as a default, you could simply set an empty string as default value. However, logically, since "#{nil}"
(nil.to_s
as well for that case) works and returns an empty string, the modulus operator version of it should work the same. What do you think?
Also a general question, how would I go about making the Rubyspec tests pass for this particular pull request? Do I open another PR for the tests in Rubyspec? If so, how do I link these two PRs to work together in the Travis CI build acceptance test?
Updated by nobu (Nobuyoshi Nakada) over 8 years ago
Unfortunately, this change conflict with rubyspec.
How should we do:
- backport the fix and remove the failed spec
- add version guard and fix only the trunk
- keep the current behavior
Updated by nobu (Nobuyoshi Nakada) over 8 years ago
- Status changed from Assigned to Closed
Applied in changeset r52530.
sprintf.c: hash default value
- sprintf.c (rb_str_format): respect default value of a hash. no
longer raises KeyError unless the default value of the hash is
nil. [ruby-core:71354] [Bug #11661]
Updated by usa (Usaku NAKAMURA) over 8 years ago
- Related to Bug #11677: 52530の変更により、sprintfの引数のhashにkeyが存在していてもvalueがnilのときにKeyErrorがでるようになってしまった。 added