Prevent recursion into returned object

[garethstockwell]

Is there any way to prevent recursion into the object returned by a filter?

For example:

from pandocfilters import Link, Str

def my_filter(key, value, format, meta):
    if key == 'Str':
        if 'something' in value:
            return Link(attr, [Str(value)], 'my_target')

The above will result in infinite recursion into the string. One possible solution would be to introduce pseudo-types NoFilterInline and NoFilterBlock, which cause pandocfilters.walk to abort recursion down a path of the AST:

from pandocfilters import NoFilterInline, Link, Str

def my_filter(key, value, format, meta):
    if key == 'Str':
        if 'something' in value:
            return Link(attr, [NoFilterInline([Str(value)])], 'my_target')

Is there a better solution?

[jgm]

This definitely seems like a flaw in the walking algorithm; I don't think we should recurse into newly introduced items like this. I'd rather just make this the default; perhaps you want to submit a PR? By the way, with lua filters it works perfectly! ```lua function Str(el) if el.text:match("something") then return pandoc.Link(pandoc.Str(el.text), "my_target", "", el.attributes) end end ```

[HashData]

hi jgm, can we merge PR #105?

[jgm]

As noted I'd prefer to just change the algorithm so it never recurses into the newly introduced nodes, rather than adding an option.