common lisp - Output prompts are on top of each other -

-

i reading book practical common lisp. typed simple cd database shown in chapter 3. see below. when run (add-cds) program result prompt containing 2 prompts on top of each other (more precisely, 1 prompt after another, on same line):

(add-cds) => title: artist:

why doing this? program should give me title: prompt first , artist: prompt after i've typed in value title: followed newline. pretty sure typed in program faithfully. how fix this?

(defvar *db* nil)  (defun make-cd (title artist rating ripped)   (list :title title :artist artist :rating rating :ripped ripped))  (defun add-record (cd) (push cd *db*))  (defun prompt-read (prompt)   (format *query-io* "~a: " prompt)   (force-output *query-io*)   (read-line *query-io*))  (defun prompt-for-cd ()   (make-cd     (prompt-read "title")     (prompt-read "artist")     (or (parse-integer (prompt-read "rating") :junk-allowed t) 0)     (y-or-n-p "ripped [y/n]")))  (defun add-cds ()   (loop (add-record (prompt-for-cd))       (if (not (y-or-n-p "another? [y/n]: ")) (return))))

what's happening newline after (add-cds) being left in input stream (because repl stops reading sees matching close parenthesis), first read-line reading blank line , returning immediately. call clear-input before calling read-line ignore , wait new input.

(defun prompt-read (prompt)   (format *query-io* "~a: " prompt)   (force-output *query-io*)   (clear-input *query-io*)   (read-line *query-io*))

Comments

Post a Comment

Popular posts from this blog

javascript - Slick Slider width recalculation -

-
i'm trying add slide in panel on slick container css. carousel works except new width not being calculated when space has been added. recalibrate once advance next slide i'd happen each time panel opened or closed. i've tried adding both margin , padding, neither makes difference. ideas? https://jsfiddle.net/mhigley/dpf7mlpl/ html: <button type="button" id="button"><i class="fa fa-arrow-right"></i></button> <aside> <h2>slide in panel</h2> <ol> <li>list item</li> <li>list item</li> <li>list item</li> <li>list item</li> <li>list item</li> </ol> </aside> <main role="main"> <div class="sections"> <section> <article> <h2>first slide</h2> <p>lorem ipsum d...
Read more

jsf - PrimeFaces Datatable - What is f:facet actually doing? -

-
looking through primefaces code in app noticed following line: <f:facet name="header">#{trainsearch.traincount} trains</f:facet> it looks overriding header, makes sense, can explain me in little more detail? what happening line of code? complete code listed below: <p:datatable id = "results" value = "#{trainsearch.trains}" var = "train" rendered="#{not empty trainsearch.trains}" styleclass = "train-search-table horizontal-border"> <f:facet name="header">#{trainsearch.traincount} trains</f:facet> <p:column headertext = "train id"> <p:panelgrid columns="1" styleclass = "train-id-grid" layout = "grid"> <h:outputtext styleclass = "train-id-label" value="#{train.traini}"/> <h:outputtex...
Read more

angular2 services - Angular 2 RC 4 Http post not firing -

-
i trying fire post request app , it's not working, tried multiple ways. don't see request being fired under network tab in chrome. not sure problem is, appreciated. import { injectable } '@angular/core'; import { http, headers } '@angular/http'; @injectable() export class userservice{ private _url="users"; constructor(private _http: http){ } checkifusernameexists(username){ return this._http.get(this._url+"/"+username) .map(response => response.json()) } createuser(user){ let headers = new headers(); headers.append('content-type', 'application/json') console.log(json.stringify(user)); return this._http.post(this._url, json.stringify(user),{headers: headers}) .map(response => response.json()) } } first need capture error , solve error: this._http.post(this._url, json.stringify(user),{headers: headers}) .subscribe( ...
Read more