Tutorial by Examples: ed

Definition of Decorator as per Wikiepdia: The Decorator pattern can be used to extend (decorate) the functionality of a certain object statically, or in some cases at run-time, independently of other instances of the same class, provided some groundwork is done at design time. Decorator attach add...

Variables of character type or of a derived type with length parameter may have the length parameter either assumed or deferred. The character variable name character(len=len) name is of length len throughout execution. Conversely the length specifier may be either character(len=*) ... ! Ass...

import pandas as pd import numpy as np np.random.seed(123) x = np.random.standard_normal(4) y = range(4) df = pd.DataFrame({'X':x, 'Y':y}) >>> df X Y 0 -1.085631 0 1 0.997345 1 2 0.282978 2 3 -1.506295 3

val num = 42d Print two decimal places for num using f println(f"$num%2.2f") 42.00 Print num using scientific notation using e println(f"$num%e") 4.200000e+01 Print num in hexadecimal with a println(f"$num%a") 0x1.5p5 Other format strings can be found ...

If you would like to test a line of macro code without needing to run an entire sub, you can type commands directly into the Immediate Window and hit ENTER to run the line. For testing the output of a line, you can precede it with a question mark ? to print directly to the Immediate Window. Altern...

Every authenticated user has a Firebase uid that's unique across all providers and is returned in the result of every authentication method. A good way to store your user's data is to create a node to keep all the users's data and to protect it using your security rules - Database { "use...

This example assumes you know how to test a Flask app using pytest Below is an API that takes a JSON input with integer values a and b e.g. {"a": 1, "b": 2}, adds them up and returns sum a + b in a JSON response e.g. {"sum": 3}. # hello_add.py from flask import Flask...

:root { --W200: 200px; --W10: 10px; } .Bx2 { width: var(--W200); height: var(--W200); margin: var(--W10); }

In Python 2, <> is a synonym for !=; likewise, `foo` is a synonym for repr(foo). Python 2.x2.7 >>> 1 <> 2 True >>> 1 <> 1 False >>> foo = 'hello world' >>> repr(foo) "'hello world'" >>> `foo` "'hello world'"...

Pass dynamic inventory to ansible-playbook: ansible-playbook -i inventory/dyn.py -l targethost my_playbook.yml python inventory/dyn.py should print out something like this: { "_meta": { "hostvars": { "10.1.0.10": { "ansible_user": ...

Get all ice cream cones that were ordered by people liking chocolate: IceCream.objects.filter(metadata__buyer__favorite_flavor='chocolate') See the note in the "Remarks" section about chaining queries.

Removing a variable name from the scope using del v, or removing an object from a collection using del v[item] or del[i:j], or removing an attribute using del v.name, or any other way of removing references to an object, does not trigger any destructor calls or any memory being freed in and of itsel...

EXTENDED_ARG = 145 # All opcodes greater than this have 2 operands HAVE_ARGUMENT = 90 # All opcodes greater than this have at least 1 operands cmp_op = ('<', '<=', '==', '!=', '>', '>=', 'in', 'not in', 'is', 'is ... # A list of comparator id's. The indecies are used as opera...

In Fortran functions and subroutines need to be explicitly declared as recursive, if they are to call themselves again, directly or indirectly. Thus, a recursive implementation of the Fibonacci series could look like this: recursive function fibonacci(term) result(fibo) integer, intent(in) :: te...

To list installed packages: $ pip list # example output docutils (0.9.1) Jinja2 (2.6) Pygments (1.5) Sphinx (1.1.2) To list outdated packages, and show the latest version available: $ pip list --outdated # example output docutils (Current: 0.9.1 Latest: 0.10) Sphinx (Current: 1.1.2 Late...

When adding indented code blocks inside a list you first need a blank line, then to indent the code further. Different flavours of Markdown have different rules for this. StackExchange requires code to be indented by 8 characters instead of the usual 4. (Spaces replaced with * for clarity): 1...

# For Python 2 compatibility. from __future__ import print_function import lxml.html import requests def main(): r = requests.get("https://httpbin.org") html_source = r.text root_element = lxml.html.fromstring(html_source) # Note root_element.xpath() gives a *...

If the values in a container have certain operators already overloaded, std::sort can be used with specialized functors to sort in either ascending or descending order: C++11 #include <vector> #include <algorithm> #include <functional> std::vector<int> v = {5,1,2,4,3};...

Managed resources are resources that the runtime's garbage collector is aware and under control of. There are many classes available in the BCL, for example, such as a SqlConnection that is a wrapper class for an unmanaged resource. These classes already implement the IDisposable interface -- it's u...

It's important to let finalization ignore managed resources. The finalizer runs on another thread -- it's possible that the managed objects don't exist anymore by the time the finalizer runs. Implementing a protected Dispose(bool) method is a common practice to ensure managed resources do not have t...