System properties are set on the Java command line using the -Dpropertyname=value syntax. They can also be added at runtime using System.setProperty(String key, String value) or via the various System.getProperties().load() methods. To get a specific system property you can use System.getProperty(String key) or System.getProperty(String key, String def). Environment variables are set in the OS, e.g. … Read more
{{ }} tells the template to print the value, this won’t work in expressions like you’re trying to do. Instead, use the {% set %} template tag and then assign the value the same way you would in normal python code. {% set testing = ‘it worked’ %} {% set another = testing %} {{ … Read more
Straight from the C# Language Specification, Identifiers (C#) : The prefix “@” enables the use of keywords as identifiers, which is useful when interfacing with other programming languages. The character @ is not actually part of the identifier, so the identifier might be seen in other languages as a normal identifier, without the prefix. An … Read more
You have to build the regex as a string: TEXTO = sys.argv[1] my_regex = r”\b(?=\w)” + re.escape(TEXTO) + r”\b(?!\w)” if re.search(my_regex, subject, re.IGNORECASE): etc. Note the use of re.escape so that if your text has special characters, they won’t be interpreted as such.
Which is better, a or b? From a performance perspective, you’d have to measure it. (And in my opinion, if you can measure a difference, the compiler isn’t very good). From a maintenance perspective, b is better. Declare and initialize variables in the same place, in the narrowest scope possible. Don’t leave a gaping hole … Read more
You can safely use the typeof operator on undefined variables. If it has been assigned any value, including null, typeof will return something other than undefined. typeof always returns a string. Therefore if (typeof maybeObject != “undefined”) { alert(“GOT THERE”); }
You must understand the difference between a class and an instance of that class. If you see a car on the street, you know immediately that it’s a car even if you can’t see which model or type. This is because you compare what you see with the class “car”. The class contains which is … Read more
title is a local variable. They only exists within its scope (current block) @title is an instance variable – and is available to all methods within the class. You can read more here: http://strugglingwithruby.blogspot.dk/2010/03/variables.html In Ruby on Rails – declaring your variables in your controller as instance variables (@title) makes them available to your view.
Using f-strings: plot.savefig(f’hanning{num}.pdf’) This was added in 3.6 and is the new preferred way. Using str.format(): plot.savefig(‘hanning{0}.pdf’.format(num)) String concatenation: plot.savefig(‘hanning’ + str(num) + ‘.pdf’) Conversion Specifier: plot.savefig(‘hanning%s.pdf’ % num) Using local variable names (neat trick): plot.savefig(‘hanning%(num)s.pdf’ % locals()) Using string.Template: plot.savefig(string.Template(‘hanning${num}.pdf’).substitute(locals())) See also: Fancier Output Formatting – The Python Tutorial Python 3’s f-Strings: An Improved … Read more
With Python 3.8 one can simply use f-string debugging feature: >>> foo = dict() >>> f'{foo=}’.split(‘=’)[0] ‘foo’ One drawback of this method is that in order to get ‘foo’ printed you have to add f'{foo=}’ yourself. In other words, you already have to know the name of the variable. In other words, the above code … Read more