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Test if a property is available on a dynamic variable
...trying to access it, unless you re-implemented the way dynamic binding is handled in the C# compiler. Which would probably include a lot of guessing, because it is implementation-defined, according to the C# specification.
So you should actually try to access the member and catch an exception, if i...
ORA-00979 not a group by expression
...ults to a single value (like MIN, MAX or SUM).
A simple example to understand why this happens: Imagine you have a database like this:
FOO BAR
0 A
0 B
and you run SELECT * FROM table GROUP BY foo. This means the database must return a single row as result with the first column 0 to fulfill t...
Invoking JavaScript code in an iframe from the parent page
Basically, I have an iframe embedded in a page and the iframe has some JavaScript routines I need to invoke from the parent page.
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Default visibility for C# classes and members (fields, methods, etc.)?
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All of the information you are looking for can be found here and here (thanks Reed Copsey):
From the first link:
Classes and structs that are declared directly within a namespace (in other words, that are not nested within other classes or structs) can be either public or internal...
What is the benefit of using $() instead of backticks in shell scripts?
There are two ways to capture the output of command line in bash :
8 Answers
8
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How to open a specific port such as 9090 in Google Compute Engine
I have 2 Google Compute Engine instances and I want to open port 9090 in both the instances. I think we need to add some firewall rules.
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What parameters should I use in a Google Maps URL to go to a lat-lon?
...uld like to produce a url for Google Maps that goes to a specific latitude and longitude. Now, I generate a url such as this:
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Spring MVC: How to perform validation?
I would like to know what is the cleanest and best way to perform form validation of user inputs. I have seen some developers implement org.springframework.validation.Validator . A question about that: I saw it validates a class. Does the class have to be filled manually with the values from the us...
Rename specific column(s) in pandas
...' else x for x in df.columns]
Or, construct a mapping using a dictionary and perform the list-comprehension with it's get operation by setting default value as the old name:
col_dict = {'gdp': 'log(gdp)', 'cap': 'cap_mod'} ## key→old name, value→new name
df.columns = [col_dict.get(x, x) fo...
What does “error: option --single-version-externally-managed not recognized” indicate?
...not recognized when pip install ing varions packages (including PyObjC and astropy ). I've never seen this error before, but it's now also showing up on travis-ci builds for which nothing has changed.
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