Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>The first half of your problem (reusing the value) is easily solved:</p> <pre><code>class LazyWrapper(object): def __init__(self, func): self.func = func self.value = None def __call__(self): if self.value is None: self.value = self.func() return self.value lazy_wrapper = LazyWrapper(lambda: function_that_generates_huge_array_slowly(0)) </code></pre> <p>but you still have to use it as <code>lazy_wrapper()</code> not <code>lasy_wrapper</code>.</p> <p>If you're going to be accessing some of the variables many times, it may be faster to use:</p> <pre><code>class LazyWrapper(object): def __init__(self, func): self.func = func def __call__(self): try: return self.value except AttributeError: self.value = self.func() return self.value </code></pre> <p>which will make the first call slower and subsequent uses faster.</p> <p><strong>Edit:</strong> I see you found a similar solution that requires you to use attributes on a class. Either way requires you rewrite every lazy variable access, so just pick whichever you like.</p> <p><em><strong>Edit 2:</em></strong> You can also do:</p> <pre><code>class YourClass(object) def __init__(self, func): self.func = func @property def x(self): try: return self.value except AttributeError: self.value = self.func() return self.value </code></pre> <p>if you want to access <code>x</code> as an instance attribute. No additional class is needed. If you don't want to change the class signature (by making it require <code>func</code>, you can hard code the function call into the property.</p>
    singulars
    1. This table or related slice is empty.
    1. POpython lazy variables? or, delayed expensive computation
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USagf
    1. USagf
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POpython lazy variables? or, delayed expensive computation
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COMaybe if instead of `__call__` you used a property, it would be possible to avoid `()` and it would be easier to search/replace. This depends on existing code.
      singulars
      1. PO
      1. US9000
    2. COI don't see how it would make any difference in search / replace? And you're just replacing `()` with something else, it seems like a subjective question which you prefer. My method is just the least code way of implementing it.
      singulars
      1. PO
      1. USagf
    3. COI like the second LazyWrapper... I'll give it a shot. The solution I found had a few too many layers of abstraction for me to wrap my head around in context.
      singulars
      1. PO
      1. USkeflavich
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload