I just want to know what is the difference between the add_action and add_filter. I just could not get it enough in the documentation of wordpress. Can anyone explain it more broader and simpler. Thank you in advance.
I have been looking at the plugin API a bit more in depth recently and I was wondering what real differences there were between action and filter hooks. They both are events that receive data as a parameter and they seem to both be able to do the same things.  Obviously I see that actions are called when actions take place and filters are called when data is manipulated, but it seems to just be a semantic naming difference.  Besides semantics and what they are used for, what real differences are there between them?
I am just curious that the following format looks good to you or not? The preamble I used is just   \documentclass[12pt,a4paper]{article}  \usepackage{amsmath} \usepackage{amsthm} \usepackage{amssymb}   I don't feel it's so good because the first paragraph has no indent but the second does. If the first paragraph is much longer, than it's fine. But if not, it looks strange. Should I leave it, or you have suggestions for this? In the absence of a signal handler, does SIGTERM behave identically to SIGKILL? Finite choice without AC Can anyone explain how we choose one sock from each of finitely many pairs without the axiom of choice?  I mean : To choose one sock from each of infinitely many pairs of socks requires the Axiom of Choice, but for shoes the Axiom is not needed.  The idea is that the two socks in a pair are identical in appearance, and so we must make an arbitrary choice if we wish to choose one of them. For shoes, we can use an explicit algorithm -- e.g., "always choose the left shoe." Why does Russell's statement mention infinitely many pairs? Well, if we only have finitely many pairs of socks, then AC is not needed -- we can choose one member of each pair using the definition of "nonempty," and we can repeat an operation finitely many times using the rules of formal logic (not discussed here). How do I switch back to python2 after Anaconda set python3 as the default? Recently, I installed  on my 15.04 and ended up with this!  :~$ python --version Python 3.5.1 :: Anaconda 2.5.0 (64-bit)  :~$ python2 --version Python 2.7.9  :~$ python3 --version Python 3.5.1 :: Anaconda 2.5.0 (64-bit)   During the last moments of installation, I did enter something as yes in hurry, and I suppose it had to do something with this. (Ok, my fault, I should have handled that carefully, but I need help now, not criticism).    AFAIK this is definitely going to break other programs. What do I do now?    What I think could work.  Can this be done using aliases?  alias python=python2   But I ain't sure. get all page IDs from wp_list_pages Etymology for “Mc‑” and “O’‑” prefix in surnames There is clearly a prefix in names like McDonald, McChrystal, O’Brian, O’Neal.  What does this Mc- and O- prefix signify? It looks like Donald, Chrystal, Brian, Neal are perfectly fine names on their own, so why is there a prefix before it? Does $\mathbb R^2$ remain connected when countably many points are removed? Does it remain path connected?  This is not homework but is in response to working several problems where countable or uncountable many points are removed and the pattern always holds.  Thank you. Render every Nth frame of an animation I want to render every Nth frame of an animation, in this case every 12th frame. This way I can play back the animation at 2fps and see if everything is going correctly.  I'm a real novice with Blender Python and cobbled this together:  import bpy  for f in range(startframe,endframe,NthFrame):     bpy.context.scene.frame_current = f     bpy.ops.render.render()     bpy.data.images['Render Result'].save_render(filepath="" + str(f) + '.png')    This kind of works, the right images are rendered and saved. However it completely freezes up Blender, and after about an hour it crashes on windows due to being unresponsive I guess. How can I fix this? Preferably I'd like it to work like rendering an animation normally works, i.e. being able to still use Blender and seeing the progress of each rendered frame. How do the radian have a unit? We have been asked to prove the above statement through the two sub-proofs:   Firstly we must prove that $e^x$ is increasing and then prove that $\log(x)$ is also an increasing function.   After we are asked to prove that using the delta-epsilion definition of a limit that $\lim_{x \to 0} e^x = 1$.   I have done all of this but still don't see where the instructor is going with this. Removing las2dem streaks from raster DEM? I've created a series of DEM files using the  tool from LAStools; however since I don't have a licensed version they have black streaks running across them. Does anyone know a good method for removing these streaks? How can I horizontally center a &lt;div&gt; within another &lt;div&gt; using CSS? &lt;div id=&quot;outer&quot;&gt;   &lt;div id=&quot;inner&quot;&gt;Foo foo&lt;/div&gt; &lt;/div&gt; Block specific URL on web browsers I want to block certain URLs on browsers. I don't want to block whole site. For example, I want to block , but not whole  domain. Is there any way I can do it? let $x,y,z,w&gt;0$,show that $$(x+y)^3+(y+z)^3+(z+w)^3+(w+x)^3\ge 8(x^2y+y^2z+z^2w+w^2x)$$  it seem use AM-GM inequality to solve it,But I can't it,Thanks Uk Visa Refused need guidelines etc,,, I am from Pakistan I applied for 4x Weeks UK family visit visa with my 6x years daughter and they refused, my refusal issue is same. I am going to quote my refusal letter.     You stated they you are employed with A----- company and Earning Rs. ____ per month in support of your application you have provided a latter from your employer. However  I am not satisfied that one document alone demonstrates that you have the employment status and earning claimed. You also state that your spouse is employer with ___ Company and Earning Rs. ____ per month in support of your application you have provided a latter from your employer However  I am not satisfied that one document alone demonstrates that you have the employment status and earning claimed with out further corroborating evidence. I note that you have declared no other personnel income, savings or assets. Based on the information provided i am not satisfied that your circumstances are as claimed and that you have demonstrated strong economic financial ties to Pakistan.  It is your responsibility to satisfy me that your circumstance in Pakistan are such that if granted leave to enter you will abide by all the conditions attached to any such leave and that you will leave the uk on completion of the proposed visit  but you have failed to do so. therefore I am not satisfied that  you are seeking a genuine visit or that you intend to leave the uk at the end of your visit  your application for visit visa has been refused  paragraph V4.2(a) and (c) I am not satisfied that you have sufficient funds to cover all reasonable costs in relation to your visit including the cost of your journey. any cost relating to dependents and the cost of any planned activities. your application for visit visa has been refused under paragraph V4.2(e).  ,,,   These objections and reasons are not as like they thinking I have my bank statement and transactions including Rs. 4 lac balance I have transactions of my salary in statement and my husband recently employed he is also have his salary transaction in the same statement because we both using our joint account.  I just want to go Uk and meet my family for 4x weeks and I am with my 6 years daughter my husband is not going with us due to his job.  Now please guide me should I go for Administration review and provide them my bank statement because my visa rejected on 26 July 2016 I still have time period for administration review OR I should reapply immediately to remove all these objections and give them more evidences I mean bank statement and our pay slips etc? Kindly guide me what to do which way will work.. Your quick help and guidelines will help me. I have a file with ANSI colors.  test.txt: \e[0;31mExample\e[0m  I would like to display the content of this file in a terminal, like cat does, but I would like to display the colors as well. For all square matrices $A$ and $B$ of the same size, it is true that $(A+B)^2 = A^2 + 2AB + B^2$? The below statement is a true/false exercise.  Statement: For all square matrices A and B of the same size, it is true that $(A + B)2 = A^2 + 2AB + B^2$.  My thought process: Since it is not a proof, I figure I can show by example and come to a valid conclusion based on such example.  My work:  Come up with a square matrix A and B let both be a 2 by 2 matrix(rows and cols must be same).  Matrix $A$:  $A = \begin{array}{ccc} 3 &amp; 5 \\ 4 &amp; 6 \\ \end{array} $  Matrix $B$:  $B =  \begin{array}{ccc} 5 &amp; 8 \\ 9 &amp; 4 \\ \end{array} $  $A + B =  \begin{array}{ccc} 8 &amp; 13 \\ 13 &amp; 10 \\ \end{array}$  $(A + B)^2 =  \begin{array}{ccc} 233 &amp; 234 \\ 234 &amp; 264 \\ \end{array}$  $A^2 =  \begin{array}{ccc} 29 &amp; 45 \\ 36 &amp; 56 \\ \end{array}$  $(AB) =  \begin{array}{ccc} 60 &amp; 44 \\ 74 &amp; 56 \\ \end{array}$  $2(AB) =  \begin{array}{ccc} 120 &amp; 88 \\ 234 &amp; 112 \\ \end{array}$  $B^2 =  \begin{array}{ccc} 97 &amp; 72 \\ 81 &amp; 88 \\ \end{array}$  $A^2 + 2AB + B^2 =  \begin{array}{ccc} 246 &amp; 205 \\ 265 &amp; 256 \\ \end{array}$  Based my above work, the answer is false.   Is there another way to approach the problem? It seems like a lot of work needed to be done for a true/false question which raised my suspicion about whether there is a better way to look at the problem. Converting KML to shapefile without losing attributes using QGIS? Does there exist an automorphism of $\mathbb{C}$ that does not keep $\mathbb{R}$ fixed? CSS to make HTML page footer stay at bottom of the page with a minimum height, but not overlap the page