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What is in your Mathematica tool bag? [closed]
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I've mentioned this before, but the tool I find most useful is an application of Reap and Sow which mimics/extends the behavior of GatherBy:
SelectEquivalents[x_List,f_:Identity, g_:Identity, h_:(#2&)]:=
Reap[Sow[g[#],{f[#]}]&/@x, _, h][[2]];
This allows me to group lists by a...
How to implement the Android ActionBar back button?
....lang.NullPointerException: Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)' on a null object reference
– Jones
Mar 15 at 21:12
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What's the need of array with zero elements?
...d it would have meant the very same thing. The authors of the Linux kernel apparently love to make things needlessly complicated and non-standard, if an option to do so reveals itself.
In older C standards, ending a struct with an empty array was known as "the struct hack". Others have already expl...
How to lazy load images in ListView in Android
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Here's what I created to hold the images that my app is currently displaying. Please note that the "Log" object in use here is my custom wrapper around the final Log class inside Android.
package com.wilson.android.library;
/*
Licensed to the Apache Software Foundation (...
Why does GCC generate 15-20% faster code if I optimize for size instead of speed?
...essor, but decrease performance on your particular processor (and the same applies to -Os). If you try the same example on different processors, you will find that on some of them benefit from -O2 while other are more favorable to -Os optimizations.
Here are the results for time ./test 0 0 on sever...
How do I use Ruby for shell scripting?
...h()
For file system operations I almost always use Pathname. This is a wrapper for many of the other file system related classes. Also useful: Dir, File...
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What is the most efficient way to store a list in the Django models?
...the root of all evil."
With that firmly in mind, let's do this! Once your apps hit a certain point, denormalizing data is very common. Done correctly, it can save numerous expensive database lookups at the cost of a little more housekeeping.
To return a list of friend names we'll need to create a ...
AfxGetApp->GetMainWnd() 与 AfxGetMainWnd() - C/C++ - 清泛网 - 专注C/C++及内核技术
AfxGetApp->GetMainWnd() 与 AfxGetMainWnd()前台线程与后台线程,AfxGetApp->GetMainWnd()与AfxGetMainWnd的不同 顾名思义，前台指看得见，既然看得见自然要有窗口，而后台是看不...前台线程与后台线程,AfxGetApp->GetMainWnd()与AfxGetMainWnd的不同
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How do I have an enum bound combobox with custom string formatting for enum values?
... I've seen a similar solution where instead of using a custom class, they mapped the enum values to a Dictionary and used the Key and Value properties as the DisplayMember and ValueMember.
– Jeff B
Jul 12 '13 at 21:39
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In a Django form, how do I make a field readonly (or disabled) so that it cannot be edited?
...ng get_readonly_fields.
Usually you should declare something like this in app/admin.py:
class ItemAdmin(admin.ModelAdmin):
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readonly_fields = ('url',)
I've adapted in this way:
# In the admin.py file
class ItemAdmin(admin.ModelAdmin):
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def get_readonly_fields(self, request...