<br><br><div class="gmail_quote">On Wed, Jun 1, 2011 at 9:56 AM, Ethan Furman <span dir="ltr"><<a href="mailto:ethan@stoneleaf.us">ethan@stoneleaf.us</a>></span> wrote:<br><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;">
<div class="im"><br></div>
Several times in that thread it was stated that<br>
<br>
--> a += 1<br>
<br>
is a shortcut for<br>
<br>
--> a.__iadd__(1)<br>
<br>
It seems to me that this is an implementation detail, and that the actual "longcut" is<br>
<br>
--> a = a + 1<br>
<br>...<br><font color="#888888">
<br>
~Ethan~<br></font></blockquote><div> </div><div>a += 1 is not a shortcut for a.__iadd__(1). It's a shortcut for a = a.__iadd(1). Otherwise this wouldn't work:</div><div><br></div><div><div><font class="Apple-style-span" face="'courier new', monospace">>>> x = (1,)</font></div>
<div><font class="Apple-style-span" face="'courier new', monospace">>>> x += (2,)</font></div><div><font class="Apple-style-span" face="'courier new', monospace">>>> x</font></div><div><font class="Apple-style-span" face="'courier new', monospace">(1, 2) </font></div>
</div><div><br></div><div>Note the difference between these two is one opcode:</div><div><br></div><div><font class="Apple-style-span" face="'courier new', monospace"><div>>>> def f(x,y):</div><div><span class="Apple-tab-span" style="white-space:pre"> </span>x += y</div>
<div><span class="Apple-tab-span" style="white-space:pre"> </span></div><div>>>> dis.dis(f)</div><div> 2 0 LOAD_FAST 0 (x)</div><div> 3 LOAD_FAST 1 (y)</div>
<div>
6 <b>INPLACE_ADD</b> </div><div> 7 STORE_FAST 0 (x)</div><div> 10 LOAD_CONST 0 (None)</div><div> 13 RETURN_VALUE </div><div>>>> def g(x,y):</div>
<div><span class="Apple-tab-span" style="white-space:pre"> </span>x = x + y</div><div><br></div><div>>>> dis.dis(g)</div><div> 2 0 LOAD_FAST 0 (x)</div><div> 3 LOAD_FAST 1 (y)</div>
<div> 6 <b>BINARY_ADD</b> </div><div> 7 STORE_FAST 0 (x)</div><div> 10 LOAD_CONST 0 (None)</div><div> 13 RETURN_VALUE </div></font></div>
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