Concatenating LazyStrings

Luke Drummond
Fri Nov 5 12:22:45 GMT 2021

Hi David

On Fri Nov 5, 2021 at 3:14 AM GMT, David Blaikie via Gdb wrote:
> If I've got a pretty printer (for instance, for llvm's Twine type (
> + ) that wants to
> pretty
> print a string made up of other strings (from other pretty printers) -
> how
> would I do that?
> Specifically, I can't figure out how to correctly concatenate a gdb
> LazyString value with another string. (even if I have to stringify the
> LazyString (making it unlazy) in the process - calling ".value()" on the
> LazyString doesn't seem to be enough - I can't seem to figure out how to
> to-string-ify that resulting gdb Value (it doesn't have a pretty printer
> that I can find - nor a to_string/str/string() function) to then
> concatenate it with another string)

`LazyString.value().format_string()` might be what you want. I've also found the
python builtin `str()` function to be usable in many places.

has the documentation if you haven't already seen it.

As an example, here's how I format an enumeration that's made up of bit-flags:

	def fmt_flags_enum(enum_type, val):
			val = int(val)
			return ' | '.join(
					gdb.Value((1 << x) & val).cast(enum_type).format_string()
					for x in range(val.bit_length())
					if (1 << x) & val

The `format_string()` converts the individual enumerators into a string that
python can concatenate with `str.join`.

Hope that helps.

All the Best


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