Accessing dict keys like an attribute?

Question

I find it more convenient to access dict keys as obj.foo instead of obj[\'foo\'], so I wrote this snippet:

class AttributeDict(dict         


        

Answer 1

What would be the caveats and pitfalls of accessing dict keys in this manner?

As @Henry suggests, one reason dotted-access may not be used in dicts is that it limits dict key names to python-valid variables, thereby restricting all possible names.

The following are examples on why dotted-access would not be helpful in general, given a dict, d:

Validity

The following attributes would be invalid in Python:

d.1_foo                           # enumerated names
d./bar                            # path names
d.21.7, d.12:30                   # decimals, time
d.""                              # empty strings
d.john doe, d.denny's             # spaces, misc punctuation 
d.3 * x                           # expressions  

Style

PEP8 conventions would impose a soft constraint on attribute naming:

A. Reserved keyword (or builtin function) names:

d.in
d.False, d.True
d.max, d.min
d.sum
d.id

If a function argument's name clashes with a reserved keyword, it is generally better to append a single trailing underscore ...

B. The case rule on methods and variable names:

Variable names follow the same convention as function names.

d.Firstname
d.Country

Use the function naming rules: lowercase with words separated by underscores as necessary to improve readability.

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Sometimes these concerns are raised in libraries like pandas, which permits dotted-access of DataFrame columns by name. The default mechanism to resolve naming restrictions is also array-notation - a string within brackets.

If these constraints do not apply to your use case, there are several options on dotted-access data structures.