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    <p>Unless you specifically act to ensure otherwise, most classes don't have helpful results for either:</p> <pre><code>&gt;&gt;&gt; class Sic(object): pass ... &gt;&gt;&gt; print str(Sic()) &lt;__main__.Sic object at 0x8b7d0&gt; &gt;&gt;&gt; print repr(Sic()) &lt;__main__.Sic object at 0x8b7d0&gt; &gt;&gt;&gt; </code></pre> <p>As you see -- no difference, and no info beyond the class and object's <code>id</code>. If you only override one of the two...:</p> <pre><code>&gt;&gt;&gt; class Sic(object): ... def __repr__(object): return 'foo' ... &gt;&gt;&gt; print str(Sic()) foo &gt;&gt;&gt; print repr(Sic()) foo &gt;&gt;&gt; class Sic(object): ... def __str__(object): return 'foo' ... &gt;&gt;&gt; print str(Sic()) foo &gt;&gt;&gt; print repr(Sic()) &lt;__main__.Sic object at 0x2617f0&gt; &gt;&gt;&gt; </code></pre> <p>as you see, if you override <code>__repr__</code>, that's ALSO used for <code>__str__</code>, but not vice versa.</p> <p>Other crucial tidbits to know: <code>__str__</code> on a built-on container uses the <code>__repr__</code>, NOT the <code>__str__</code>, for the items it contains. And, despite the words on the subject found in typical docs, hardly anybody bothers making the <code>__repr__</code> of objects be a string that <code>eval</code> may use to build an equal object (it's just too hard, AND not knowing how the relevant module was actually imported makes it actually flat out impossible).</p> <p>So, my advice: focus on making <code>__str__</code> reasonably human-readable, and <code>__repr__</code> as unambiguous as you possibly can, even if that interferes with the fuzzy unattainable goal of making <code>__repr__</code>'s returned value acceptable as input to <code>__eval__</code>!</p>
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    1. USAlex Martelli
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    1. COIn my unit tests I always check that `eval(repr(foo))` evaluates to an object equal to `foo`. You're right that it won't work outside of my test cases since I don't know how the module is imported, but this at least ensures that it works in _some_ predictable context. I think this a good way of evaluating if the result of `__repr__` is explicit enough. Doing this in a unit test also helps ensure that `__repr__` follows changes to the class.
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      1. USSteven T. Snyder
 

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