flutter: after adding disposable, my stack design widget is dead

I added the disposable widget in my flutter listview application. After adding it, my stack design widget becomes a dead code and the list is not displayed in my application.
It shows as & # 39; instance of tasks & # 39 ;. but without discarding the list it is working fine. Please brother, help me out of this problem. my code below

Widget compilation (BuildContext context) {
back new scaffolding (
resizeToAvoidBottomInset: false,
body: column (
crossAxisAlignment: CrossAxisAlignment.center,
mainAxisAlignment: MainAxisAlignment.spaceBetween,
children: (
_myAppBar (context),
width: MediaQuery.of (context) .size.width,
height: MediaQuery.of (context) .size.height – 80,
son: ListView.builder (
itemCount: items.length,
itemBuilder: (context, index) {
final item = items (index);

                    return Dismissible(
          // Each Dismissible must contain a Key. Keys allow Flutter to
          // uniquely identify widgets.
          key: new ObjectKey(items(index)),
          // Provide a function that tells the app
          // what to do after an item has been swiped away.
          onDismissed: (direction) {
            // Remove the item from the data source.
            setState(() {

            // Then show a snackbar.
                .showSnackBar(SnackBar(content: Text("$item dismissed")));
          // Show a red background as the item is swiped away.
          background: Container(color: Colors.red),
          child: ListTile(title: Text('$item')),

       return  Stack(children: (
                                                                      // The containers in the background
                                                                      Column(children: (
                                                                      padding: EdgeInsets.only(left: 8.0, right: 8.0),
                                                                          child: Container(
                                                                            width: MediaQuery.of(context).size.width,
                                                                            height: 80.0,
                                                                            child: Padding(
                                                                              padding: EdgeInsets.only(top: 8.0, bottom: 8.0),
                                                                              child: Material(
                                                                                color: Colors.white,
                                                                                elevation: 14.0,
                                                                                shadowColor: Color(0x802196F3),
                                                                                child: Center(
                                                                                  child: Padding(
                                                                                    padding: EdgeInsets.all(8.0),
                                                                                    child: Row(
                                                                                      children: (
                                                                                          style: TextStyle(
                                                                                              color: Colors.black,
                                                                                              fontSize: 20.0),
                                                                                          children: (
                                                                                              style: TextStyle(
                                                                                                  color: Colors.black,
                                                                                                  fontSize: 18.0,
                                                                                                  fontWeight: FontWeight.bold),
                                                                                              style: TextStyle(
                                                                                                  color: Colors.black,
                                                                                                  fontSize: 16.0),
                                                                         // ..........................dismiss

                   //.................end dismiss




I await my list that I make for firestore.
but it only shows – instance of & # 39; tasks & # 39;

Without discarding the list is working.

Game design: unusual leveling mechanism?

On the leveling up of the players, most (or maybe all …?) Roleplaying games are like this:

  1. Kill enemies (for experience points)
  2. Level up (for more attack power)
  3. Repeat

It's fun at low levels, but later, it gets boring and boring; The game becomes more like increasing your numbers to see more numbers.

I am doing a role play. I am thinking of giving the player mini-missions for each level to level up. For example, to reach level 2, the player must meet the following:

  • Earn 10 EXP points.
  • Find an old jar.
  • Kill a blue wolf with a single attack.

So my question is: Are there games that have done this (I have not seen or heard of any)? Is it a good or a bad idea? Even if there are games that have done this technique, why do most (or all) role-playing games go with the process of killing, leveling up and repeating?

WTB – Paid post on a web design / marketing forum | Forum Promotion

I end my forum pause again and I have thought about preparing a web design / marketing forum for my ideal client (medical professionals who need websites).

The forum is here: http://marketing.themedically.com/

As you can see, the main themes are:

  • Medical SEO,
  • Design and programming,
  • Content Marketing,
  • Conversion optimization,
  • Junk mail
  • Offline advertising

Do not be scared by the medical niche, it is more to boost my SEO and reach this ideal person, but we all know that ANY website can really use these things, even if they are not in the medical industry. All websites need good SEO, a look at the conversion rate optimization, good email marketing campaigns, proper advertising outside the Internet and all the site problems are the same, no matter what niche we are talking about .

I would need 3 paid forum posters at this time to accelerate the creation of my content in the forums and boost its initial development.

If you want to post to a webmaster forum (after all, that's what it is), send me a PM with your rates and availability.

I am seeing approximately 100 posts / month, which means an average of 3-4 / day. It doesn't have to be every day, but ideally it should be spread evenly, so we don't have periods of activity and inactivity for weeks. This can also allow me to create more interesting threads and make it more attractive (and its work easier).

As you can see, we do not have game threads and we do not have too much general chat, since I would like to take full advantage of SEO work, so I am looking for quality publications that are, as I am, extremely passionate about websites and sufficiently informed To have a decent conversation.

Thanks in advance for helping me with this:

Here I will keep you informed about the availability of the publication plans:



GUI design: conceptual, semantic, syntactic and lexical levels

In relation to symbols or icons, the conceptual level It is defined as the mental model of the spectator; semantic level it is the meaning it conveys; syntactic level It is attributed to its aesthetic quality or its screen layout;

How would you describe the "lexical level" in connection with the iconography?

I will design a brochure, booklet, e-book, triptych, company profile in 8 hours – Other opportunities to earn money

Hello everyone,

Welcome to my concert. I will design a brochure, booklet, ebook, triple, company profile in 8 hours

I will design a 2 page brochure template in 8 hours.

the user information it's an advertisement double fold template. the frills They are promotional documents, mainly used to present a company, organization, products or services and inform potential clients or members of the public about the benefits.

Why should you buy my concert?

  • I will make a high quality brochure design, flyer design that will speak well about your brand.

  • I will design 16 more pages of PSD, PDF, EPS and Ai brochure templates

  • Infographic and all elements 100% editable.

  • Extra fast delivery in 8 hours (2 page booklet)

  • Free unlimited revisions.

  • High resolution printable files.

My services

  • User information

  • Annual report

  • frills

  • tri-fold brochure

  • bifold

  • user information

  • company profile

  • business proposal
  • Ebook

  • magazine etc.

  • postcard design

  • visiting card

Why choose my service?

  1. 24/7 support.
  2. Quick response and friendly customer service.
  3. Free unlimited review

★★ 100% satisfaction guarantee! ★★

NB: Before placing your order, be sure to talk to us.

Design: Node.js error handling through each layer

What is it he The best way to handle errors in a Node.js application. This could apply to any language, but I still don't understand how to do it correctly. The questions are always who handle mistakes, does it make sense to continually throw to the top and who records what?

Take a simple example of a user system where you can retrieve users from a database and "log in" if the credentials match.

Database layer

// connects to a mongo db 
class UserDatabase(){
   async getUser(filter){
       // this can throw if connection is dead
       let user = await this.collections.users.findOne(filter);
       return user;

Application layer

// makes calls to the db class to "login" a user
class UserApp {
    async loginUser(email, password){
       let user = await this.db.getUser({email});
           return false;
       if(user.password === options.password){
           return true;

REST layer

// calls the API from REST calls
class UserRestApi {
    async loginUser(request, response){
        let result = await this.app.loginUser(request.body.email, request.body.password);
            response.status = 200;
        else {
            response.status = 401;

There are currently 0 error handling. We can fail almost everywhere with exceptions not detected. But is there any point in the capture at the lowest level? Suppose getUser() It fails because the Mongodb connection dies. I can catch it and register it there, but do I throw it back, again and again, and register it again, again and again and again? Makes sense? It would end in this case with 2-3 repeated records.

Not sure how to address this.

database design: storage of 450,000,000,000 data points in a two-time data warehouse

I am really looking for guidance on a proper way to address the persistence and recovery of 450 billion data points. The details:

  • 15,000 days of history (approximately 40 years)
  • 2,000 columns / properties
  • 45 billion = 15,000 * 15,000 * 2,000
  • 30,000,000 inserts per day (15,000 shares * 1 day * 2,000 properties)

Warnings: Some properties have values ​​for almost every day, e.g. price. Some properties have very few values ​​per year, p. earnings. Therefore, the above estimates are upper limits.

Insertions occur throughout the day and do not need to be "fast." Readings occur during a short window in the morning and should be "quick"; Recover all data and perform commercial calculations in 1 hour.

The properties are bitemporal: they have a data date and an effective date. The last one is to support corrections to erroneous data and backtesting.

Some properties are calculated from other properties, that is, we read data, calculate a derived value and then insert the result.

There is no official budget for this project, so assume that high specification hardware, cloud infrastructure and custom software are all possibilities.

So, any suggestions on a persistence technology suitable for this problem? Any design considerations you should be thinking about?

Python: I'm not sure which design pattern works best in my case

I currently have a great ontology like this:
enter the description of the image here

There are different categories of variants and each one can be somatic or germinal.
There are more common behaviors among the same variants, such as somatic CNVs and germline CNVs have more common behaviors due to the fact that both are CNV. But there are also some common behaviors between small somatic and somatic fusions because they are somatic (this design does not take that kind of reuse into account).

So I'm thinking of changing it to something else, a strategy pattern With a factory like this:
enter the description of the image here

But this meets the problem that I have too many behaviors and are quite specific for a kind of variant. Example behaviors:

  • calculate_position ()
  • Calculate_gene_location ()
  • Calculate_log2foldchange ()

All these do something different depending on the type of variant. And they are quite short functions. So I will end up creating many small kinds of behavior and end with a more extensive ontology.

Not all variants have the same behavior: some have protein_prediction () or split_reads (). At the end of the day I want to be able to get 8 classes with the behaviors I need.

Any ideas for a better way to organize my code?

Website design – Multiline text in navigation

Your users will not want to navigate to the page just to find out what the title is.

If I saw "Practical En …", I wouldn't know what that page is.

I prefer to have more space dedicated to navigation to be able to read the full titles.

There are many navigation patterns and can be found with some web searches, but they can vary greatly depending on the device and the destination platform.

Too difficult for programmers to write a CSS design?

In my internal work, I keep hearing how backend programmers need the Bootstrap framework because they "don't have an interface mindset" and need a standard library to collaborate.

I don't understand. Those programmers are smart enough to learn to program and build a back-end infrastructure for an advanced web application. However, can't they even bother using even CSS Flexbox and CSS Grid to write a simple page? And Bootstrap is your answer to this "problem"? How? When writing dazzling HTML with full utility classes you need to learn in addition to CSS?

@deathshadow I would say that it is another "3 & # 39; s". However, I still find it difficult to understand how someone smart enough to program can have trouble using CSS. And, somehow, they conclude that Bootstrap requires less work than writing a simple Flexbox code.