Posts by mgibsonbr • 80,631 points
861 posts
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4
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answer87
viewsA: would like to know how I do this effect aque in css
You need to adjust the border-radius of its element, if it is large enough the element will be round: img { background-color: blue; width: 200px; height: 200px; } .capa { width: 210px; height:…
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votes6
answers34111
viewsA: What is and what is an abstract class for?
The function of an abstract class is to implement partially a type. The best example I know is the class AbstractList Java: while the interface List defines a kind, useful but complex, it does not…
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3
votes1
answer72
viewsA: Jquery does not return second image in the list
Your problem is that the image has no siblings, she is only link daughter (a), so that the next will not return anything. To select the next image, it is necessary to go up to the parent, grab the…
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11
votes2
answers2359
viewsA: Password encryption
That would be good practice? No. The recommended way to protect a password is through a slow hash (PBKDF2, Bcrypt or scrypt). You’re right to say that a fast hash is ineffective, but you realize…
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3
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answer125
viewsQ: How to pass arguments dynamically to a new call?
If I have a Javascript function and want to call it by passing a list of arguments, use apply: var x = f(1,2,3); var x = f.apply(null, [1,2,3]); For the first time, I came across a case where I need…
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answers931
viewsA: What is artificial intelligence?
There is no consensus on the best definition for "Artificial Intelligence" (or "Computational Intelligence", another widely used term). For example, a definition quite simple but that doesn’t say…
artificial-intelligenceanswered mgibsonbr 80,631 -
8
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answer1130
viewsA: When using async and Defer, is the order of the scripts respected?
TL;DR - async execute at any time and in any order, defer and "normal" execute in the order they are declared (but all defer after all the "normal"). Find an accurate specification of the behavior…
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6
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answer90
viewsA: What’s wrong with my chained list?
Your problem is that in remove you are not updating the ultimo. So when you remove the last element the field ultimo points to a node (cell) that no longer belongs to the list. When trying to add…
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2
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answer78
viewsA: Doubt receive 3 numbers and tell if the first is equal to the sum of the other two in LISP
The parenthesis of the if: (defun maior(n1 n2 n3) (if (=(+ n2 n3)n1) (format t "~D é maior que ~D e ~D!" n1 n2 n3) ) ) Example in the ideone.…
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answer1130
viewsQ: When using async and Defer, is the order of the scripts respected?
For a single script, the load/run order in presence or not of attributes async and defer is clear: with nothing, loads and executes immediately, with async loads in parallel and performs at the end…
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votes3
answers267
viewsA: I’d like to know how Vagrant works
The main advantage of Vagrant in my opinion is to allow each developer to use the native resources of their environment during development (e.g., text editor, IDE, etc.) execution environment…
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19
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answers8421
viewsA: What is Cross-Cutting and what is its relationship to Aspect Oriented Programming (AOP)?
Many aspects of a system are designed hierarchical and/or in layering. This assumes that not every component of the system needs to interact with every other component, and the organization of the…
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8
votes1
answer122
viewsQ: A bit mask can/should be typed?
In most programming languages, when you want to create a bit mask you usually use an integer type and operations bitwise (and, or, xor, not, shift left, shift right...). However, although nothing…
language-designasked mgibsonbr 80,631 -
6
votes2
answers460
viewsA: How to replace Eval() with another expression
In fact this change will not produce the expected result. However, in Javascript all property can be accessed through brackets. So that: foo.bar It’s the same as that: foo["bar"] And by the way,…
javascriptanswered mgibsonbr 80,631 -
13
votes4
answers7972
viewsA: How can I make a copy of an array without reference?
You can use the method slice without passing arguments to a blank copy (source), or something like the angular.copy for a deep copy: var b = a.slice(); // ou var b = angular.copy(a); In your example…
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9
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answers133
viewsA: get original HTML entities with javascript
The original HTML entities are not preserved when the Markup of the document is interpreted (Parsed) for browser, so that they are not available to you to consult them via Javascript or any other…
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9
votes2
answers2503
viewsA: Javascript, action on a selected text
You can use the attributes selectionStart and selectionEnd of textarea to determine which section of the same is selected. Then just replace this section in its value (value). Example (takes the…
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5
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answers189
viewsA: Regex - Operator "." - Meta character capture
PHP regular expressions do not support Unicode by default, unless you use the flag u: preg_match('~aten..o~', $string, $match); print_r($match); Array ( ) preg_match('/aten..o/u', $string, $match);…
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answer1630
viewsA: Saving a JSON in Database vs Relationship?
A relational database, normalized, assumes that each attribute (value of a column in a table) is atomic, that is, it cannot be broken into smaller pieces from the point of view of the relational…
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votes3
answers441
viewsA: Why is it not very common to use do/while?
Perhaps because it is simpler to determine the invariant loop through the while (and of for) than of do..while. And invariant is something that is always necessary to understand the semantics of the…
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1
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answers142
viewsA: what is the best way to create elements?
One option is to use a ready text, add in the DOM, and then change only what you need. Assuming jQuery: var item = "<li class=\"col-md-2 \">"+ " <button type=\"button\" class=\"btn…
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answer54
viewsA: For an unordered set of listeners what is the best java.util.Set implementation to use?
Use a CopyOnWriteArraySet. According to the documentation, it is the ideal implementation for cases where "set sizes usually remain small" and "read-only operations are much more frequent than…
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answer3644
viewsA: "Noreversematch at/" on Django, when I try to put a link on the button
A mistake NoReverseMatch is a consequence of Django not being able to find a URL in his mapping system that solves for a given view, either in the template (tag url) or in Python code (reverse). In…
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answer218
viewsA: Is AES in PHP safe?
No. Generally speaking, it is only safe to use libraries that have undergone a lot of scrutiny by experts in this area. Not only does the implementation need to be correct, but it needs to take into…
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answers435
viewsA: What is the rule for converting a binary value to a negative number and vice versa?
Negative numbers - at least for the whole type - are usually represented by complement of two. This means that the most significant digit determines whether the number will be positive or negative.…
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answers16866
viewsA: How to check Undefined correctly in Javascript
Depends on what you want to test: Whether or not a variable with that name exists In that case, I would try to perform an operation on her and observe a ReferenceError: var x; try { x + 1;…
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answers666
viewsA: Check file extension in template - Django
You can use the filter slice, it works the same way as the array slicing python. That is, if you want the extension, just look at the last 4 characters of the file name (assuming a 3 letter…
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votes2
answers1166
viewsA: How to return a query in JSON format with extra values and custom Keys?
I would use list understandings in both cases: return HttpResponse(json.dumps({ "principal": True, "cadastros":[{ "id":p.id, "STATUS":p.status, "podeEscrever":p.podeescrever,…
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votes2
answers557
viewsQ: Can I upload to a subfolder using Filefield?
When I define one FileField (or ImageField), I need to specify a upload_to: campo1 = models.FileField(upload_to="uploads") campo2 = models.ImageField(upload_to="img/%Y/%m/%d") In the first case, all…
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answers161
viewsA: How do I manage my messaging flow?
You need a queue: whenever the sendToServer is called, put the data in the queue instead of sending it straight. At the end, of the two: If the system is in a state that allows messages to be sent,…
javascriptanswered mgibsonbr 80,631 -
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answers874
viewsA: Is it possible to prevent injection of external resources and requests for greater security?
Updating: the browsers modern implement the Content Security Policy (CSP), which allow websites to guide the browser to allow/block several things. More details on reply from Guilherme Nascimento.…
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answers3667
viewsA: Are there objective advantages to a language being "case sensitive" or not?
The main advantage of case sensitive is to increase the possible set of symbols (names). The main impact on traditional languages is the creation of an implicit relationship between a type and an…
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4
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answer5739
viewsA: Javascript/Jquery copy-paste command (Ctrl + c)
Note: this solution is specific pro Internet Explorer You can do this through the function execCommand: Create a range (range) and choose which part of your document will be covered by that range:…
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7
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answer401
viewsQ: How to create a function in the J language?
How to create a function in the J language? All the examples I found online show only how to describe functions through a Fork: media =: +/ % # media 1 2 3 4 2.5 The code above (+/ % #) is the same…
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3
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answers69
viewsA: Give same value independent of the order
I see two options: 1) you compare both strings, and concatenate them so that the "minor" (in lexicographic order) is always first, and then hash the concatenated strings; 2) you hash each string…
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5
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answer344
viewsA: Organize list with more than one criterion in case of a tie
Assuming the comparison functions are not overly expensive, what you can do is return a tuple with the result of the first function in position 0 and the result of the second position 1:…
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21
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answer778
viewsQ: What are error-correcting codes?
What they are and how they work error-correcting codes (error-correcting code)? I’ve seen this concept for example in QR Code (where partially damaged and/or imperfectly captured code is still…
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1
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answer1044
viewsA: Save the result of a variable to the Mysql database using python passed as parameter
From what I understand, your difficulty is in passing variables to your SQL query, right? The command execute has a parameter params which receives a tuple/list or dictionary. In it you associate…
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1
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answer2956
viewsA: Manipulate list and add list items in Prolog
Prolog arithmetic is based on the predicate is/2: the right side needs to contain a concrete expression (i.e. cannot have free variables), which will be evaluated and the result unified with the…
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3
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answer2242
viewsA: How to scroll through a list in Prolog to find a specific item
There are two ways to go through a list, the most "natural" - using recursion, which you probably already know - or through a combination of member with findall/bagof/setof. I will show both forms,…
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2
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answer218
viewsA: function include in LISP
In Lisp, a list has two parts: the "head" (car) and the "tail" (cdr). The head is a common element of the list, and the tail is the rest of the list (or nil, if the list is over). You can create a…
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5
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answer1262
viewsA: How to get out of a loop with hotkeys
First, you need a way to detect that the user is trying to press a key without actually reading that key (otherwise, the loop would stop and wait for the user input). According to that question on…
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votes2
answers10986
viewsA: What is JSONP and how does it work?
JSONP (JSON with padding) is a technique designed to circumvent a limitation of the use of Ajax in browsers: the fact that the Policy of Same Origin does not allow the domain A make an Ajax request…
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28
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answer2421
viewsA: How does this code that generates a maze work?
This code generates a maze randomly using the method "deep-sea search" and then draws it on the screen using ASCII art. An example of output would be:…
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answer1346
viewsA: Difference between get_context_data and get_queryset and code improvement (Django)
These methods have totally different purposes: get_context_data provides context data to be used when rendering a template. This does not necessarily involve the ORM, so that you could for example…
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answer175
viewsA: What is the difference between the declaration forms of Generics with out and in?
The out and the in make the type generic covariant and countervariant, respectively. An example of a covariant type is the IEnumerable: public interface IEnumerable <out T>: IEnumerable {…
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answers10409
viewsA: How do you display "Press ENTER to continue" in Python 3.4?
To demand the Enter (i.e. ignore everything the user enters until the Enter is pressed), see hugomg response. In case you accept any key (i.e. return whatever the user has typed, without waiting for…
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answer869
viewsA: How to verify which items on the list meet a certain condition?
Prolog uses an execution strategy called in-depth search with setback. This means that given two calls, he will try to find a solution for the first, then one for the second, and if for some reason…
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answers821
viewsA: What is an object returned in parentheses?
In Java, a single element in parentheses is identical to the same element without any parentheses. Only when there are two or more elements does the parenthesis matter - be it improving readability…
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answers439
viewsA: Converting values for calculation to JQ
If you want to make calculations with the value of input, then you need to convert them to number. The problem is that you can’t save the number back to a input because it would go back to being a…