Add extra information to FormatException.

Add extra information to FormatException.

R=floitsch@google.com

Committed: https://code.google.com/p/dart/source/detail?r=38181

[Lasse Reichstein Nielsen, 2014-07-11 12:17:06]

This was something I had already done indirectly in two places, so it seemed
like worth generalizing.

[floitsch, 2014-07-11 16:03:27]

LGTM.

https://codereview.chromium.org/389603002/diff/1/sdk/lib/core/exceptions.dart
File sdk/lib/core/exceptions.dart (right):

https://codereview.chromium.org/389603002/diff/1/sdk/lib/core/exceptions.dart...
sdk/lib/core/exceptions.dart:66: * Optionally also supply the source that had
the incorrect format, and
The optional argument [source] and [position] point to the location where the
format error was detected.

You have to say that for strings with new-lines it will print "line: ..."

[Lasse Reichstein Nielsen, 2014-07-14 07:47:55]

Committed patchset #2 manually as r38181 (presubmit successful).

[nweiz, 2014-07-14 19:33:50]

DBC

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
File sdk/lib/core/exceptions.dart (right):

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
sdk/lib/core/exceptions.dart:48: * The source that caused the error.
The documentation and name doesn't make it clear at all that this is supposed to
be the source text. I assumed that it was the URL or path to the source.

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
sdk/lib/core/exceptions.dart:55: final source;
It would be a lot more useful to consumers of this class if this had a mandated
type, especially since [toString] completely ignores it if it's anything other
than a String.

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
sdk/lib/core/exceptions.dart:57: * The position in source where the error was
detected.
Please be clearer about what you mean by "position". I assume it's "characters
from the beginning of the source"?

For what it's worth, the source map package refers to this as "offset" rather
than "position".

[Lasse Reichstein Nielsen, 2014-07-15 08:55:59]

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
File sdk/lib/core/exceptions.dart (right):

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
sdk/lib/core/exceptions.dart:48: * The source that caused the error.
I'll try to make it more explicit, including the words "The actual source .."

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
sdk/lib/core/exceptions.dart:55: final source;
I don't want to mandate a type. It will almost always be a String, but you
should also be able to use this exception when parsing a byte-buffer.

A FormatException should never be unexpected, so the receiver would know which
input was given to the function throwing it. If that function is parsing byte
lists, the source will be that byte list, and the caller can decide what to do
with it.

https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
sdk/lib/core/exceptions.dart:57: * The position in source where the error was
detected.
I like "offset", so I changed it everywhere.
Also tried to explain what it means (if source is a string, it's the index of a
code unit).

[nweiz, 2014-07-15 18:29:06]

On 2014/07/15 08:55:59, Lasse Reichstein Nielsen wrote:
>
https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
> File sdk/lib/core/exceptions.dart (right):
> 
>
https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
> sdk/lib/core/exceptions.dart:48: * The source that caused the error.
> I'll try to make it more explicit, including the words "The actual source .."
> 
>
https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
> sdk/lib/core/exceptions.dart:55: final source;
> I don't want to mandate a type. It will almost always be a String, but you
> should also be able to use this exception when parsing a byte-buffer.
> 
> A FormatException should never be unexpected, so the receiver would know which
> input was given to the function throwing it. If that function is parsing byte
> lists, the source will be that byte list, and the caller can decide what to do
> with it.
> 
>
https://codereview.chromium.org/389603002/diff/20001/sdk/lib/core/exceptions....
> sdk/lib/core/exceptions.dart:57: * The position in source where the error was
> detected.
> I like "offset", so I changed it everywhere.
> Also tried to explain what it means (if source is a string, it's the index of
a
> code unit).

SGTM