component.set('v.acc.Name', 'Name from 3!');
To:

var acc = component.get('v.acc');
acc.Name = 'Name from 3!';
component.set('v.acc', acc);
And everything will work.

Here is why you are seeing this behavior, and why the workaround is working:

The rule to remember: all changes are propagated down, but only propagated up when they affect the… Read more

understanding System Events In Lightning Components – Part 1
In this blog we'll explore how System events in Lightning Components work to help write better code and solve potential performance issues due to race condition and rerendering of components.
Lightning Components Framework comes with a set of “system” events to notify components… Read more

You nearly made me forget the syntax there !! I've corrected the trigger above, try that to see if it works.

You need to have a for loop to iterate over all the records that have invoked the trigger.

Also a before trigger makes more sense, since you're manipulating values on the triggering records.

trigger Peachtree_items_process… Read more

JSON Deserialization Techniques in Salesforce
Brenda FinnIf you have ever been given a JSON object and needed to parse it in Apex, then you may have run into some of the same issues I did so read on. JSON, which stands for JavaScript Object Notation, is widely used due to its ability to define the structure of an object and its values at the… Read more

VF page:

<apex:page controller="Account_Filter" docType="html-5.0">
<apex:form >
<apex:pageBlock >

<!--Search and filter button-->
<apex:pageBlockButtons location="top">
<apex:commandButton value="Search" action="{!searchaccounts}" />
<apex:commandButton value="Show Selected Accounts"… Read more

<apex:outputPanel id=”repeating”>
<apex:repeat value=”{!change}” var=”c”>
<apex:selectRadio value=”{!save}”  action=”{!saveInformation}”>
<apex:selectOption itemValue=”{!c}” itemLabel=”{!c}”  />
</apex:selectRadio>
</apex:repeat>
<apex:actionSupport event=”onchange” reRender=”repeating”… Read more

Use Third-Party Data to Update and Add Records to Salesforce
A rule set up by your Salesforce admin compares your accounts, contacts, and leads to data from a third-party source—Lightning Data or Data.com. Depending on how your admin sets up the rule, your records are updated as information changes. Or your admin can give you purchase credits to… Read more

Fulfill Orders Faster
Seamlessly generate orders from quotes to quickly get products and services delivered to your customers.
Flexible for Evolving Customer Needs
Split quotes into multiple orders, manage future dated orders, and modify with point- and-click.
360-Degree View of the Customer
Quickly generate contracts with all contract… Read more

for (Messaging.Inboundemail.BinaryAttachment bAttachment : email.binaryAttachments) {

Attachment attachment = new Attachment();
// attach to the newly created contact record
attachment.ParentId = contact.Id;
attachment.Name = bAttachment.filename;
attachment.Body = bAttachment.body;
insert attachment;
}

Considerations for Lookup Filters
REQUIRED EDITIONS AND USER PERMISSIONS
Available in: both Salesforce Classic (not available in all orgs) and Lightning Experience
Available in: All Editions except for Database.com.

USER PERMISSIONS NEEDED
To manage lookup filters:
Customize Application
On the Fields page, the   icon indicates all fields… Read more

Create, Preview, and Activate Quote Templates
Define the look of your company’s quote PDFs by creating templates that your sales reps can choose when they create quote PDFs.

REQUIRED EDITIONS AND USER PERMISSIONS
Available in: Salesforce Classic (not available in all orgs) and Lightning Experience
Available… Read more

We generally avoid applying for loop in apex code as it will break governer rule so do the query for your program.

Presuming that you're dynamically creating components (e.g. c1 and c2), you have total control over the aura:id. A component cannot define its own aura:id, only the aura:id for children within itself. From here, it follows that you're trying to figure out what type of component you're dealing with. For that, we use Component#getType. This… Read more

Messages can be displayed in notices and toasts. Notices alert users to system-related issues and updates. Toasts enable you to provide feedback and serve as a confirmation mechanism after the user takes an action.

Include one <lightning:notificationsLibrary aura:id="notifLib"/> tag in the component that triggers the notifications,… Read more

I believe you are trying to associate a single contact to multiple accounts. This functionality was released in Spring 16' and is implemented through a Salesforce Junction object - AccountContactRelation.

I assume you have already enabled this functionality through the UI and a parent Account is declared for this Contact.

I have modified your… Read more

Share Files Via Link
Available in: Salesforce Classic
Available in: Essentials, Group, Enterprise, Professional, Performance, Unlimited, Contact Manager, and Developer Editions
You can share a file with anyone by creating a file link and sending it through email or IM. Creating a link generates an encrypted URL that you can send to any… Read more