Leave original placeholder if attribute is not present in passed object

[vdiez]

When using named arguments, value in output for the field is currently replaced to 'undefined'. This change leaves the original placeholder instead of changing its value.

[vdiez]

any option to have this PR merged?

[alexei]

Sorry - what is this about?

[vdiez]

Imagine this use case where placeholders to replace are spread among different objects:

let command = 'cp %(source)s %(target)s' 
let params1 = {source: '/mnt/file1'} 
let params2 = {target: '/mnt/file2'}

With this change I can chain them like that:

let command = sprintf(command, params1)
let command = sprintf(command, params2)

With current version I cannot, because after the first call, the placeholder %(target)s will be replaced by undefined.

[alexei]

This has been asked and discussed before, and I stand by my opinion that one should validate their data.

Besides, use cases such as this one could be implemented using Proxy objects where they e.g. return %(property)s for each missing property.

[vdiez]

In my case data is validated, but there is a workflow where each parameter/-s is provided on a different step and by different modules. Of course, my example was way simpler than real use case.

My opinion is that this PR keeps the result more stateless and in any case i doubt having undefined in the final string is preferable and cleaner when the property is not found.

I understand the subjectivity of this. Feel free to close the PR

[alexei]

Does it work if params1, params2 are Proxy objects?

[vdiez]

ok, i was doing a long explanation of why not until I understood what you meant.

so yes, Proxy object should work. I'll do that then :)

cheers