31 lines
2.7 KiB
Markdown
31 lines
2.7 KiB
Markdown
# Message System
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Tidy has quite complex warning/error messaging system. This is all about adding a **new** warning or error message to **libTidy**.
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First assign the message a key value. This is done in `tidyenum.h`, in one of the two enumerations that are listed there.
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1. `tidyMessageCodes` - starts with the value `tidyMessageCodes_first = 500`, and it must be first. These are messages that appear in Tidy's report list, the list that's emitted telling you what Tidy did to your code. **However** don't modify this enum directly. You'll modify a preprocessor macro instead.
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2. `tidyMessagesMisc` - starts with the value `tidyMessagesMisc_first = tidyMessageCodes_last`. These are messages that are emitted that tell you general information, such as further advice.
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All enum values are only ever used by name within **libTidy** (and incidentally, should only ever be used by name in your client applications; never trust the value!), so feel free to enter new strings wherever they make the most sense. There are already existing categories (marked by comments), or feel free to create a new category if that's best.
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As mentioned above, `tidyMessageCodes` messaged must be defined in one of the existing macros named like `FOREACH_...(FN)`, such as `FOREACH_MSG_ENTITIES(FN)`. These macros ensure that another data structure used for localization and key lookup is updated automatically any time strings are added or removed, thus limiting the possibility of developer error.
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## Step 1
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So in this case I want to add 3 warning messages: `BAD_SURROGATE_PAIR`, `BAD_SURROGATE_TAIL`, and `BAD_SURROGATE_LEAD`. Because these are error messages, they belong in the `tidyErrorCodes` enum, and they fit into nicely into the macro beginning `FOREACH_MSG_ENCODING(FN)`.
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## Step 2
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The next step is adding a `format` string to `language_en.h`. This string may later be translated to various supported language strings, but at present it is important that the other language translated strings, like `language_fr.h`, `language_es.h`, etc, keep the same format order.
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Where to add this seems a bit of a mess, but in general things are grouped by where they're used in `libTidy`, and often in alphabetical order within those groups. Here I've added them relative to where they were placed in the other enums and structs.
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Depending on which of the output routines you use (consult `message.c`) you may be able to use parameters such as `%u` and `%s` in your format strings. The available data is currently limited to the available message output routines, but perhaps generalizing this in order to make more data available will be a nice focus of Tidy 5.5. Please don't use `printf` for message output within **libTidy**.
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eof;
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