c# - How to fix this lambda expression? -

-

i have function sorting multiple user selected columns:

public override void sort(sortfields sortfields) {     if (sortfields == null || sortfields.count() == 0) return;      var res = filtereditems.orderby(o => o[sortfields[0].name], sortfields[0].ascending ? comparer : comparerdesc);      (int x = 1; x < sortfields.count(); x++)         res = res.thenby(o => o[sortfields[x].name], sortfields[x].ascending ? comparer : comparerdesc);      filtereditems = new bindinglist<t>(res.tolist());      if (listchanged != null)         listchanged(this, new listchangedeventargs(listchangedtype.reset, null)); }

the problem, of course, when res.tolist() called x has been incremented 1 greater highest index in list , throws error. know go ahead , tolist() after each sort defeats purpose , isn't guaranteed sort correctly linq providers. i'm sure there's simple solution this... want tell me is? :)

it looks may getting tripped closure on variable x.

that single variable incremented on every iteration of loop. it's incremented 1 last time, @ point it's 1 greater number of items in "sortfields", conditional statement evaluates false, , for loop ends.

as user2864740 pointed out, , eric states in article:

closures close on variables, not on values.

so when call tolist(), chained thenby statements retain final value of variable x, 1 greater highest index.

instead, assign incrementer intermediary variable inside loop. when call tolist(), final value of x won't matter.

for (int x = 1; x < sortfields.count(); x++) {     int y = x;     res = res.thenby(o => o[sortfields[y].name], sortfields[y].ascending ? comparer : comparerdesc); }

also eric's article, (hopefully) being corrected soon, though in foreach loops apparently, not for loops:

in c# 5, loop variable of foreach logically inside loop, , therefore closures close on fresh copy of variable each time. "for" loop not changed.


Comments

Post a Comment

Popular posts from this blog

database - VFP Grid + SQL server 2008 - grid not showing correctly -

-
i having problem, have grid called "gridbasica" , this: thisform.gridbase.recordsource = "sgviemp" sgviemp cursor made executing select sqlserver command sqlexec. when want modify registry, go form , the update there. so, when come form grid, grid isnt grid anymore, big white rectangle. reading around said: delete recordsource , asingt again. thisform.gridbase.recordsource = "" *--i sqlexe here thisform.gridbase.recordsource = "sgviemp" i , works, but, when click button modify again cursos updated modify form doesnt load fields did first time. could me out that? thanks in advance. --------------- edit ------------------ i have been doing recommended: lnselect = select(0) n = sqlexec(thisform.conexion,"select emp_ccodigo codigo, emp_cnombre 'nombre o razon social', emp_cnumrif 'r.i.f' sgviempr","sgviemp1") set echo on suspend select sgviemp zap in sgviemp *-- browse *--zaps correct
Read more

jquery - Set jPicker field to empty value -

-
im using jpicker color selector in form. have clear value set window/icon 'no color selected' state. i've tried following: $(':input[name="color"]').val(''); //access value directly. (does not affect jpicker) 2: $.jpicker.list[0].color.active.val('hex', '', this); //set color black , input value 000000, instead of empty string 3: $.jpicker.list[0].color.active.val(null, '', this); //does nothing none of 3 methods seems behave properly. in advance. this works me :) $.jpicker.list[0].color.active.val('v', null); here example: http://jsfiddle.net/3up7n/
Read more

.htaccess - htaccess convert request to clean url and add slash at the end of the url -

-
ok , searched more 4 days , more 20 posts here in stach or in websites without kind of success first here htaccess file rewriteengine on rewriterule ^([a-za-z0-9_]+)/?$ index.php?page=$1 [nc] rewriterule ^([a-za-z0-9_]+)\/([a-za-z0-9_]+)\/?$ index.php?page=$1&action=$2 [nc] i tried many codes 1 worked me can call request , works me www.example.com/pagename => www.example.com/index.php?page=pagename here questions , please provide me information "in detail" understand code well 1- how convert request automatically www.example.com/index.php?page=pagename www.example.com/pagename 2- if tried add slash @ end shows me page without images or styling mean www.example.com/pagename => works www.example.com/pagename/ => doesn't work that's :) for first part need 301 rule this: rewritecond %{the_request} /index\.php\?page=([^\s&]+) [nc] rewriterule ^ /%1? [r=301,l] for second part use absolute path in css, js, images files r
Read more