Allow use with system espeak-ng and vanilla phonemizer

[evq]

Describe the feature

The current espeakng-loader mechanism for shipping espeak-ng doesn't play nicely with packaging on distros where it is expected to use the system packaging ( e.g. NixOS ).

I think this can be easily achieved by conditionally importing espeakng_loader only when it is installed and shorting out the Tokenizer init method if it is not present. In this case with a vanilla phonemizer install, I believe it would take care of loading the library.

[thewh1teagle]

Espeakng-loader should respect system wide espeak

[thewh1teagle]

Hmm it doesn't
I'm not sure how to handle it correctly, i wanted that it will work out of the box for most users.
If I'll add the logic you mentioned, how will you remove espeakng-loader? kokoro-onnx depends on it by default in it's dependencies

[evq]

My use case involves packaging kokoro-onnx as a system package so the pyproject.toml deps are not used. If the code allows for it, said packaging can simply depend on the existing espeak-ng and phonemizer system packages.

[thewh1teagle]

My use case involves packaging kokoro-onnx as a system package so the pyproject.toml deps are not used. If the code allows for it, said packaging can simply depend on the existing espeak-ng and phonemizer system packages.

Unlike Rust Python doesn't have feature flags to keep espeakng-loader by default and turn it off by choice.
I'll see how this can be achieved. as for phonemizer - I suggest use phonemizer-fork. there's some fixes such as caching/memory leaks

[evq]

Agreed - something like rust default features would be ideal here.

As a first step though, just landing the code changes to allow for espeakng-loader to be missing would suffice for making a system package out of this library.

In that case, you're depending on other system packages to resolve the dependencies - not using pip or similar. So the pyproject.toml and uv.lock specification of dependencies would be effectively ignored. ( Technically in the case of the Nix package I am working on, the deps listed in pyproject.toml are used to sanity check the redefinition of dependencies in terms of system packages and hence need to be ignored. This is done by adding to the pythonRemoveDeps section. In any case, this first step of making the code change would allow me to drop one of the patch files which is more of a maintenance burden. )

Good to know about phonemizer-fork having fixes / improvements beyond the custom espeak path. I will have to look at the upstream Nix packaging for phonemizer to see what would be involved in packaging phonemizer-fork as well.