Add support to load a yaml from a file

While ruamel.yaml supports any kind of stream for its load method, this is not the case for strictyaml, which currently checks the following:

    if stream_type not in ("<type 'unicode'>", "<type 'str'>", "<class 'str'>"):
        raise TypeError("StrictYAML can only read a string of valid YAML.")

I think strictyaml.load should implicitly accept all the types that are supported by the underlying call to ruamel.yaml.load.

I also strongly believe you should avoid using this kind of type comparisons and use isinstance instead. Also consider adapting validators.py where types are checked using == which is clearly a bad idea 😉

[AlexandreDecan]

What if I don’t want to store a whole document in a string? What if I want to read a stream from the network? Why should I use an explicit str, not any other (lazy?) iterable? The stream api is quite common in Python, and ruamel.yaml provides support for it. It is expected that your load function also supports it.

I believe you should either focus on (1) bringing a replacement of ruamel.yaml API with type safety support (built on top of ruamel.yaml for instance), or (2) bringing a tool that allows to validate a json (before it is loaded in ruamel) or to validate the structure returned by ruamel.yaml.load.

This is an ugly line of code but it’s necessary to be python 2/3 compatible.

I don’t understand what is wrong about using isinstance in py2/3.

[crdoconnor]

I’m sorry, in this case, I don’t see any good reason to break the duck typing philosophy of Python.

This philosophy is in direct contradiction to line 2 of the zen of python: explicit is better than implicit.

I don’t personally believe that either philosophy should be used dogmatically - there is a case by case trade off to be made between both. In this case I believe there’s enough complication under the hood as it is to justify not putting even more implicit behavior in.

For objects that implement __ str __ and return YAML it isn’t a problem just do strictyaml.load(str(object)). For file handles it’s not a huge deal to just do .read().

I was expecting strictyaml to handle the same kind of cases than ruamel.yaml.

It’s stricter.